Okay, sweetie! A banjo is a fun musical instrument!
Imagine a big, round balloon. The banjo has a body that is like that balloon, but it's made of wood! This round part is called the 'body' of the banjo.
Now, think of a stretchy blanket or a piece of paper that you can pull tightly. The banjo has something thin and tight like that stretched over the wooden round body. This helps make beautiful sounds when you play it!
So, a banjo is a wooden round part that has a thin piece stretched on top to make music. Isn't that cool?