That he wants to have sex with you. Beyond that, it really depends on the guy.
There’s nothing wrong, per se, with sex on the first date, but it’s a bit forward to assume you’ve made such a good impression that you’re leaping straight into the sack. I wouldn’t be surprised if he came off as a wee bit egotistical, or a bit like he was checking off the points on a list in his head.
I wasn’t on that date: Maybe it went spectacularly and he really thought he had a chance. But if you’re turned off, you’re turned off, and if you’re not looking for a hook-up, I’d move on.