Okay, so you know how sometimes dogs play and chase each other around, right? Well, sometimes people have airplanes and they chase each other around in the sky. This is called a dogfight.
In a dogfight, two airplanes try to outmaneuver each other and shoot each other with special guns that shoot bullets. The pilots have to be very skilled and quick to fly their planes in loops and turns to try and get behind their opponent and shoot them down.
It's kind of like a really fast and exciting game of tag, but in the sky! But, just like how we don't want dogs to actually hurt each other when they play, in a real dogfight, the goal is to "shoot down" the other person's plane without actually hurting anyone. It's just for fun and to show off who is the better pilot.