A girl that is not responsible sexually. A girl that is very vocal about her sexual activities will make her seem like more of a slut. As far as a virgin talking openly about sex, it is usually more about how you are talking about it. You can still talk about sex with out sounding like a slut.
I have had more sexual partners than a certain group of my friends. We got to talking about it and for a moment I felt like a man slut. But really it was just the group of people I was with.
Slut girl is - in my opinion. Girl that sleeps quite often with different guys. Nothing wrong in liking sex, to be honest it is a VERY good thing. Just as long you don't share your self with too many random guys.
Same goes probably with the guys. Keep sticking every girl you can't - No respect in that.
Try actually knowing the girl and even might try to date her - That is what turns you in a real man.
Talking about sex stuff doesent turn you into a slut lol :D