Self-defense knowledge is great, but I don't know how useful it would be in the situation you're talking about.

I think I know what country you're writing about, if it's the one that has frequent news stories about women being attacked.

It's a societal problem. I can see why the girls stay at home, if losing your life is a real possibility if you go out.

I can't think of any easy solution to this problem. Until your society starts to condemn the behavior of those harassing men, or they start to be prosecuted by the law, it's hard to see anything changing.