I'm going out with some friends this weekend and extended the invitation to a guy I just met. He said he is looking forward to it and plans on buying me a drink.

In general, when a guy offers to get a girl a drink what does it mean?

I hardly know the guy. We have mutual friends though so it's not completely weird. I'm not interested in him, but I haven't written him off completely. My question was more in general, not even in my situation. Most of the time women hear that if a guy is interested he will get her a drink. But how true is that?