This is a sprite

 

It can be any thing, person, or place you want it to be. You can control what a sprite does. They can only do those things if they know how to do them. Sprites already know how to do some things, but it is your job to make sprites do more complicated things by using the few simple things that they already do know how to do. So in a way, you are teaching the sprite what to do. You can teach it to walk, run, jump, talk, or anything else you are clever enough to teach them to do.

You can tell a sprite to do something it already knows by putting a Script Block into the Script Window. To pick which Sprite you are controlling, select it from the window on the bottom right. Your sprites can be seen in action in your World Preview Window.