Better than Luke and any other character in the SW universe at her same age, “because reasons”, without explaination. I would accept all of this had the movie gave me a logical in-universe explaination, even just some hint.
Considering she defeated an almost complete dark Jedi on her own, with no enstablished training at all, she probably doesn’t even need to train with Luke anymore 😄

P.S.: It’s like seeing James Bond suddenly being able to fly, and in no way you could’ve known that he’s just using some kind of jetpack or magnets technology hidden inside his jacket.