A sequel is a movie or book that continues the story of another one. It's like chapter two of your favorite novel.
When people talk about sequels, they usually mean a new film or book that happens after the events of the first one. Imagine you loved the adventure in "The Lord of the Rings," and now there's a whole new movie where Frodo is all grown up with his own family - that's a sequel. Sometimes sequels are just as popular as the original, but other times they don't quite live up to our expectations.
It's worth noting that when you're writing or making art, a sequel can also mean creating something that continues the story in a more general sense, not necessarily right after the events of the first thing. For example, if you wrote a short story and then later wrote another one with some of the same characters but set at a different time, that's a sort of sequel too.
The events, collectively, which follow a previously mentioned event; the aftermath.
