A girl can indicate you at the age of the girl in the dream. This is true regardless of your gender. If you are male it means that there are issues with your mother / female side that were triggered at the age of the girl in the dream. If you are a woman it can be any event at that age around either parent.
A girl can also symbolize your female side needs development to maturity.
We each have both male and female aspects to ourselves. Dreams always encourage you to restore balance to this energy mix. In fact that is one of the main purposes of your life.