I have one bump down there it doesn't hurt and the bump is hard. is it herpes?

Probably not herpes: Herpes doesn't cause firm bumps, and never causes any kind of bump that persists more than a day or two without changing quickly into blister/pimples and then open sores. The only STDs that cause firm painless bumps are genital warts and molluscum contagiosum. If you continue in doubt about the cause of this, see a doctor soon for proper diagnosis. Good luck!