What is a BindableEvent and what can I do with it?

So I've been reading and I discovered a BindableEvent. I read more and it said "I can make my own events" I was confused by making my own events since I thought it was impossible to do.

Anyway since I discovered them, I kinda know what functions they have but I don't really understand how it can be used to make a custom event. I need help understanding it. Thanks for viewing