Self-propelled anti-aircraft weapon

Okay, so imagine playing a game of tag, but instead of touching people to tag them, you have a machine that shoots little balls at them to try and "tag" them. But this game takes place in the sky and the "people" you're trying to tag are actually airplanes!

Now, you don't want the airplanes to tag you back, so you build a special machine that can move by itself and shoot those little balls really fast and really far. This machine is called a self-propelled anti-aircraft weapon.

The machine has wheels or tracks like a tank, so it can move around on the ground by itself. It also has a big gun on top that can shoot really fast and really far. The gun is controlled by a person inside the machine who aims and shoots at the airplanes.

The self-propelled anti-aircraft weapon is like a big and powerful toy that people use to protect themselves and their stuff from bad guys who come from the sky.