Jason doesn't get magic. Oh, he's seen it before. Everything from his own experiences with the Lazarus Pit - if you could call that cursed thing 'magic' - to some of the weird crap that goes on in Metropolis, he's encountered magic. But he doesn't, like, know how it works. He doesn't get it. 'Magic' is a pretty broad term. He's probably most familiar with the kind of thing Zatana does? But that's not the only sort of magic out there. It'd be like saying botany was the only form of science out there. And really? It all just kind of goes over his head.
Not that he's got anything against magic, strictly speaking. Aside from a general 'doesn't like when it's used against him', and he can say that for a lot of things. He loves guns, for example. Doesn't like when those are used against him either. Y'know? It's a vibe. He doesn't get magic, so it makes him kind of uncomfortable, and he doesn't really want that to make him uncomfortable around you by proxy? And it won't do to be all wigged out by your whole magic thing, not if you're gonna be working together. His solution to this has been insisting on extra training with you, to try and get himself... well, 'used to it'.
The point is, Jason doesn't need you to explain how all your kooky magic stuff works. It's just gonna go in one ear and out the other. He's just gotta learn how to work with it, see what it does. What to expect. What you're capable of. How to utilize your abilities with the rest of the team's. That sort of thing. Its not that he's not interested, he just knows he won't get it.
"Nah, you don't have to explain it to me. Just show me again. I'll figure it out."