Okay kiddo, have you ever seen a gymnast doing a cartwheel or a figure skater spinning on ice? They are moving in what we call the transverse plane.
Let's imagine that you have a big piece of paper, and you drew a line across it from left to right. That's what we call the transverse plane. It's a horizontal plane that divides your body into two sections: the top or superior part and the bottom or inferior part.
Think of your body as a sandwich, with the transverse plane being the layer of bread in the middle. Everything on top of the bread is the upper part, and everything below it is the lower part.
When you do a cartwheel, your body is moving around that imaginary line. So, your arms and legs pass from one side of the transverse plane to the other as you roll over.
In the same way, you can imagine a figure skater spinning around the transverse plane. As they spin, their arms and legs move from one side to the other of the imaginary line, always staying parallel to the ground.
So, the transverse plane is like a line across your body that separates the upper part from the lower part. When you move around it, you are moving in the transverse plane. Cool, huh?