Okay kiddo, so let me explain to you what "fungible" means.
Imagine you have a bunch of different toys, like legos, action figures, and dolls. They are all different and unique, right? Now imagine you have a bag of candy, like M&Ms or Skittles. Even though each piece of candy is a little different in color or shape, they are all pretty much the same thing, right?
Well, when we talk about something being "fungible," it means it's like the bag of candy – each one is pretty much the same as the others, and you can exchange them easily without any problems. For example, if I have 5 dollars and you have 5 dollars, we can trade and each end up with the same thing – 5 dollars. The individual bills might look a little different, but they are all worth the same amount and can be used interchangeably.
So when we say something is "fungible," it means it's easy to exchange for something else that is the same. This can apply to money, goods, or even things like votes in an election. It's all about things being essentially interchangeable with one another.