Example of storyboard
What is it? A storyboard tells the story of an animation like a comic book.
Purpose? You can easily make changes to your storyboard and creates an image of how your script is going to turn out. 
How to make one? They are usually drawn on paper with a pencil but sometimes made on computers. They are brief drawings in each box, it doesn't have to be neat. Just using basic shapes and stick figures.