"Mm? Ah, yes, it is. English, then." Not a universal translator situation. "So you're human. An Earth-variant, or something else?" It's half asked to himself, half to her, and he doesn't really pause to let her answer before he launches into the explanation.

"Yes," he says, "but here I'm referring to ballroom in a more general sense, as a category of dance involving two people as partners. Usually there's an element of formal dance to it, but it can contain many different styles. You'd be shocked at the profusion that it can contain, in fact, given that the last two centuries have expanded the category by adding what aliens can do."