They're part of the Harry Potter movies, but like... extra-extra-prequels? Way before any of the regular Harry Potter stuff takes place.
The first one's about Newt Scamander and all his creatures and how he travels around to find them and study them and save them. And I guess also sort of about this kid named Credence who's got some weird stuff going on. But mostly Newt. Oh, and Jacob is Newt's friend who's a muggle- or a no-maj, I guess, but they changed the word from the books and other movies and I like muggle way better anyway- and Tina is this girl who he's maybe sort of got a crush on and Queenie is her sister who can read minds.
And then the second one is about young Dumbledore (like, pre-big-beard Dumbledore) and young Grindelwald (played by Johnny Depp, gross) and how they're sort of maybe in love but also probably are going to end up killing each other? It's a whole thing.