Probably proving once again that Dave Filoni (the guy largely responsible for both The Clone Wars and Rebels) is doing more for Star Wars than the films are, this is the first live action Star Wars series. Jon Favreau (who is a pretty big Star Wars fan, seemingly) is the showrunner, with Filoni as executive producer. It stars Pedro Pascal (Oberyn Martell from Game of Thrones), Gina Carano (an MMA fighter and American Gladiator), Giancarlo Esposito (Gus from Breaking Bad) and, apparently, Werner Herzog.
It's set a few years after the Battle of Endor, following the exploits of a Mandalorian gunslinger for hire.
...and that's about as much as we know. It's more Star Wars, probably showing the grittier side of the franchise, and I get the feeling that it's going after the Game of Thrones fans. It's probably the reason I'll cave and subscribe to Disney+, because I'd forgotten it was happening until this afternoon.