He doesn't really follow the explanation, though he stores it away to figure out later. 'Host' kind of sounds like a euphemism for 'prostitute', but she's a little young for that sort of thing.

"Don't worry, I won't leave you behind. We'll have plenty of time to get acquainted." He was planning to make a solo escape, but he can't just leave a pretty girl by her lonesome in this place. Besides, if they're in a magical realm like he thinks, a human might not last here very long.