Hello and welcome
well airsoft hits and any pain is relative, some people really feel it some dont, like others have said it depends on the person, where they are hit, there pain threshold, etc etc. A normal hit i would describe as a sharp "sting" fading after a sec or too, the worst hit i have had was from 2m away to my err .... how to put this .... plumbs ... that hurt alot

did i curl up on the floor ... yes i did. did it put me off ... No!

B)
i wouldn't worry too much, every woman/lady/girl that i have seen on the airsoft field, has given every and any bloke a run for they money! it seems the minute they get a rifle, and on the field, they transform into being utterly fearless and dam hard too boot B)
If you have any worries, go along to a site, have a chat, tell them you have never played and would like to know what the fuss is about, as you are interested etc etc, and see if they might take you out with a Marshall as a observer for a quick look during a game, see if you like what you see. Dont forget to check out the new player threads, loads of information there

and feel free to ask any questions you have, we were all new players once
Last thing, for your first time/game i would advise a woodland site, as you get too see the enemy before they can hit you (dependin on cover/size etc) they dont just walk round corners like in tight CQB sites <_<