[Roxas really isn't sure what to make of all this, but something tells him he better fill this guy in before they get to the school.]

Okay, so you have a wand. That means that you're a wizard and can use magic. Like the spell I was doing earlier.

This train's going to Hogwarts, which is a school for wizards.

I gotta admit that this feels kinda weird explaining all this since you don't look like a first year.