He plays Arthur Curry/Aquaman in the DC cinematic universe, and the upcoming Aquaman movie (duh).
The film is likely to start at Aquaman’s birth. “He was born with powers but he never really harnessed them, honed them,” said Jason Momoa in an interview at San Diego Comic-Con. “Obviously this is his whole origin story. We've seen him in Justice League, which is maybe two minutes of his old life, so we get to see where he came from.”
We will be seeing Aquaman face off with his half-brother Orm, who took the throne and is trying to unite the seven underwater kingdoms to declare war on the surface world, because he believes that humanity is the reason the seas are so polluted (and he’s not wrong).