Vaginas and labia are sort of weird that way. They are made up of all sorts of glands that keep the area moist and sometimes those glands get backed up and it can look like acne. It’s not the same thing as acne other places on your body but it can cause a sort of lumpy appearance to things. The good news is you just leave these bumps alone (don’t try popping it like a pimple) and they usually go away on their own over time. If they are really hurting, that’s different and you should see your healthcare provider. If you shave or wax, you are more likely to get these sorts of bumps because the hair actually keeps the glands busy so they can’t get backed up as easily. I’m not saying you need to go “natural” if you don’t like that, but know that the two are associated.
Acne on your vagina doesn’t have to have anything to do with sexual activity. All of your skin has pores, and all pores can turn into pimples (acne). Especially if you’re waxing or shaving.
If the bumps are very painful, or they are actually inside of your vagina (inside your body), you should have them looked at by your healthcare provider.