It is normal to have hair in or on your bum for a girl.
Hair on your bum as a girl or women is natural and is normal on both boys, girls and women and men.
The hair on your bum and other parts of the body are a natural part of human anatomy and has various functions and purposes including thermoregulation and protection.
Many people including girls and boys or women and men have some amount of hair in their bum or bottom area.
Although the amount of hair and type of hair on your bum cam vary from person to person.
Some girls even have some facial hair although not all women or girls do.
If you don't like the hair on your butt or bum you can shave the butt hair or bum hair off if you want too.
It's not a necessity for your health but if you don't like the hair in those areas you can certainly shave it off to remove it.
Some people prefer to remove the butt hair by shaving it or trimming it for comfort and aesthetic reasons but it's not really necessary.
Some men even shave their pubic hair around their balls as they hate the hair there as well.