Okay kiddo, so you know how to color a picture right? You take your crayons and color inside the lines to make a nice picture.
Well, imagine if you wanted to put a picture of a 3D teddy bear on your computer. You can't just stick it on there like a regular photo. You need to make sure it's wrapped around the teddy bear properly.
That's where UV mapping comes in. It's like taking the 3D parts of the teddy bear and flattening them out onto a 2D surface like a map. This way you can see all the little details of the bear's face and fingers and make sure they are in the right place.
Once you have the 2D map, you can add the picture of the teddy bear to it like a sticker. By doing this, when you put the 2D map back onto the 3D teddy bear, the picture will wrap around the bear perfectly!
So that's what UV mapping is, a way to take a 3D object and wrap a 2D picture onto it the right way. It's like putting a sticker on your teddy bear, but you need to use a special map to make sure it's in the right spot!