Most people seem to like making small characters. I have a tendency to make most of my characters on the tall side (I even have two with max height) and they're always towering above the rest. Even my middle-height characters seem to be tall compared to other players.
Especially female characters seem to be on the short side. Maybe people think it looks better or something.
I don't think there's any good way to convert the height marker into feet or centimeters. And I think 5'10-6'0 is pretty tall anyway, so you shouldn't mind if your character is taller than most players (I'm about 5'6 in real life, which is about an average height for men and towering for a woman). Just go with the height that feels best for the character, don't try to make it into an exact number.