Everything in these three short lines is defined by what isn't there. We're told there are no pool balls colliding and no ping pong balls bouncing, so the poem is built entirely from absence. Both sounds belong to places where people gather to play: a game room, a basement, a bar. By naming only the noises that aren't happening, the speaker makes us listen to a silence that used to be filled.
The poem never says why things are quiet, and it doesn't say how the speaker feels. That's part of its power. Judging by the choice of sounds, which are bright, clicking, and a little playful, the quiet seems like a loss. It could be an empty room, a place that has closed, or people who are no longer around. The mood is spare, still, and faintly lonely. The short lines, with "ping" and "pong" split across a line break, even mimic the bounce that's missing, leaving a gap where the sound should be.