Okay kiddo, have you ever played with your tablet or phone and touched the screen to make things happen? A dual-touchscreen is like having two screens that can do that! They are connected together so you can see things on both screens at the same time.
Think of it like a book with two pages that you can touch and swipe to turn. Imagine you're reading a story and you want to look at the pictures more closely, you might touch the picture on one page and it will get bigger on the other page. Or if you're playing a game, you might use one screen to control your character and the other screen to see where you're going.
It's kind of like having two eyes instead of one, because you can see more things at once. But instead of just looking with your eyes, you can touch and control things with your fingers. Pretty cool, huh?