Perspective is like looking at things in a very special way. You know how you can stand in front of something and see it just like it is? That's one way of looking at it - straight on.
But what if you want to draw that thing? You can't just put it on paper and draw around it, because then it would look flat and boring. So instead, you have to use perspective.
Perspective is a way of drawing things so that they look more like they do in real life. You can draw things up close or far away, and they'll always look like they're the right size and shape.
The trick to perspective is to make things look smaller the farther away they are. Think about looking down a long, straight road. The road looks like it gets smaller and smaller as it gets farther away. That's what perspective does.
So, to draw something using perspective, you have to start with a horizon line. That's a line across the page where the sky meets the ground. Then you draw a vanishing point, which is the point where all the lines converge. This makes things look like they're going off into the distance.
Then you can start drawing your object using these guidelines. Draw the part closest to you bigger, and make it get smaller as it gets farther away. And soon you have a drawing that looks like it's 3D, even if it's just on a flat piece of paper!