The wheels of an airplane are called landing gear. Think of landing gear like the shoes you wear when you walk. Just like shoes help you move around on the ground, landing gear helps the airplane move on the ground too!
When the airplane is ready to go up in the sky, it needs to take off. The landing gear helps it roll down the runway really fast before it jumps into the air! And when the airplane comes back down, the landing gear is there to land safely on the runway again.
So, without landing gear, airplanes wouldn’t be able to move, take off, or land. It’s super important, just like how you need your shoes to walk around!