There are three different "lenses" that we can use to answer this question.
What is "ball"?
Here's a description of a similar ball game played by the Aztecs
These balls... were solid, of a certain resin or gum which is called ulli [rubber] which is very light in weight and bounces like an inflated ball.... The ballgame was called tlaxtli or tlachtli. The court consisted of two walls with some twenty or thirty feet of distance between them and each was up to forty or fifty feet in length. The floor and walls were heavily plastered, the latter having some one and a half estados [nearly ten feet] in height. In the middle of the court was a line made especially for the game; and in the middle of the walls, halfway down the playing stretch, were two stones like millstones perforated in the middle, facing each other, and they each had holes wide enough that the ball could fit into each of them. And whoever placed the ball there won the game. They did not play with their hands but hit the ball with their flanks. For playing they wore gloves on their hands and a leather apron on their flanks to hit the ball (Sahagún 1938, II.viii.10, pp. 297-298).
(the online version of Allen J. Christenson's translation)
The Game's Role in the Plot
Just to summarise, the general plot of the Popol Vuh is one of a creation myth. It tells the story of how the gods created the worlds, the animals, and of the god's several attempts to create humans.
An important thing to note is that the reason behind the failure of the gods several attempts to create humans is that their attempts could not speak the names of the gods (e.g. know of them or worship them). Here's an example of this (this passage accounts why just creating animals was insufficient):
“Speak therefore our names. Worship us, for we are your Mother and your Father. Say this, therefore: ‘Huracan, Youngest Thunderbolt, and Sudden Thunderbolt, Heart of Sky and Heart of Earth, Framer and Shaper, She Who Has Borne Children and He Who Has Begotten Sons.’ Speak! Call upon us! Worship us!” they were told.
But they did not succeed. They did not speak like people. They only squawked and chattered and roared. Their speech was unrecognizable, for each cried out in a
When they heard this, the Framer and the Shaper said, “Their speech did not
turn out well.”
And again they said to each other:
“They were not able to speak our names. We are their Framer and their Shaper.
This is not good,” said She Who Has Borne Children and He Who Has Begotten Sons to
(the online version of Allen J. Christenson's translation)
Xibalba (the underworld) doesn't appear until after three failed creation attempts (the second and third attempts failed for the same reason as the first creation attempt). They first appear to oppose the fathers of the twins, "One Hunahpu and Seven Hunahpu," who, it is important to note, were "born to Xpiyacoc and Xmucane" (two of the seven gods who created the world) (Christenson).
“What is happening on the surface of the earth? They are just stomping about and
shouting. May they be summoned here therefore. They shall come to play ball, and we
shall defeat them. They have simply failed to honor us. They have neither honor nor
respect. Certainly they act arrogantly here over our heads,” said therefore all
those of Xibalba.
It should become clear that the lords of Xibalba are an opposing force to the creation god(desses). Not only are they the lords of death, but they, like the lords of creation, also want recognition from humans. As explained in the online book Esotericism of the Popol Vuh1 (which uses a different translation of the Popol Vuh):
We have here a contest between opposing forces, since those of Xibalbá cannot tolerate that " 'anyone greater than they, or any having greater power, should exist,' they all said unanimously." From this passage it is seen that the organization of the false gods is similar to that of the true since, like the latter, the false gods compose a sevenfold entity whose components must get together and reach decisions by a unanimity.
In fact, when the Lords of Xibalba are defeated, their power is restricted, paving the way for the creation gods and goddesses to create humans:
“Very well. Here then is our word that we declare to you. Hearken all
you of Xibalba; for never again will you or your posterity be great.
Your offerings also will never again be great. They will henceforth be
reduced to croton sap. No longer will clean blood be yours. Unto you
will be given only worn-out griddles and pots, only flimsy and brittle
Thus began their devastation, the ruin of their being called upon in
worship. Their glory was not great in the past, for they wanted only
conflict with the people of ancient times. Surely they were not true
From the plot perspective, the game "ball" is simply a competition to resolve the conflict, and the story wouldn't be much different if they played chess or another game.
(Just to clarify the plot: One Hunahpu and Seven Hunahpu are defeated by Xibalba, but their sons learn to play ball, go to Xibalba, and defeat the Lords of Xibalba. Afterwords, humans are finally created.)
The Symbolic Interpretation of the Game
However, another way of looking at the game is as a symbol representing the sky. From Esotericism of the Popol Vuh:
Besides symbolizing the sun's relative position in the order of its rising and its daily trajectory, Hunahpú and Ixbalamqué, playing alone for a long time on opposite sides of the court, represent the position of the sun and the moon at opposing solstices, just as this continues to be depicted on Chortí altars. All this unmistakably reflects a gradual progress in astronomic and cosmogonic knowledge.
The Popol Vuh is the only American source to speak of the origin of the ball game and place it in time. Not only does it tell us of the game's ethnological antiquity, it also explains its symbolism. It in fact establishes a parallel between the ball players and the solar gods, which from the angles of the universe — to employ the phraseology of the Chumayel manuscript — meet in the center, in this case in the ball court, where they can convert themselves into two and even four persons with no loss of their theogonic individuality, at once a unity and a multiplicity. During the ball game they wear their resplendent ceremonial gear — that is, they exhibit their insignia as solar deities. Two by two they come from the eastern and western sectors of the cosmos and, meeting in the center, forge themselves into the individuality of Heart of Heaven. This fusion of a number of forms under "one single head," as the Chortís say, is expressed in the principal rule of the game which is that the players can touch the ball only with their body but never with their heads, feet, or arms; each time this happens a point is given the other team. The continual contact of two or four bodies with a single ball makes clear the monotheistic principle whereby the deity integrates itself through the union of its hypostases. This idea is objectified in the group of ball players unable to use their heads or extremities since the ball — the symbol of the Star or Sun god — is alternatively the head of each. This figure of a single-headed god having many bodies is characteristic of Maya thought. We need only to remember Oxlahun-oc ("it of the thirteen feet"), who is mentioned in the Chilam Balam of Chumayel. The motion of the ball imitates the trajectory of the sun, a figure that the Chortí actors also reproduce in their dramatization of this part of the Popol Vuh. Besides this, the Quiché codex represents the descent of god-Seven from the Center of Heaven to the center of the earth by the solar bird which, coming down from on high, "came to see them play." As said, in Chortí religious allegory the bird of prey, which is the mask, nahual, or messenger of the deity of Heaven, descends vertically to the center of the earth — like the sun's rays — when the daystar goes through the zenith, symbolizing the descent of divine grace.
This interpretation lends a new interpretation to the text: Xibalba, the "Lords of the subterrene regions" (Esotericism) are in conflict with the lords of the sky (the creators of the world) over power over the living world. The punishment of the Lords of Xibalba ("you... shall no longer be allowed to play ball."2) reflects that Xibalba is restricted to a subteranian sphere, and that the power of death is limited. This may be one of the reasons why the gods can then create humans who "can speak their name."
However, we don't know enough to know without a doubt the real symbolism behind the ball game3. The conquistadors deliberately supressed indiginous culture when they conquored central america, and only four written mayan documents remain. It's impossible to understate the destruction that these cultures faced, and we are very fortunate that texts like the Popol Vuh still exist.4
1 I am continuously amazed at the quality of sources on mythology available online. Why would anyone want to read wikipedia?
2 This line does not occur in the Christenson translation, but the Lords of Xibalba still faced severe restrictions on their power.
3 There is disagreement about the meaning of the ball game.
4 A good account of the translation can be found on JStor (behind a paywall). Another account, which also discusses the cultural destruction of the maya, is located in the preamble of the online version of Allen J. Christenson's translation.