A girl is a young female person, usually a child or teenager. This is the most common meaning. It means a female who is not an adult yet.
The girl is playing with dolls.
My sister is a cute girl.
Sometimes, people use 'girl' to talk about a young woman, not a child. It is informal and friendly. Adults can also be called girls in this way.
She is a smart girl at work.
That girl is very kind to me.
'Girl' is sometimes used to mean a daughter. Parents may call their female child their girl. It shows family relation.
My girl is starting school today.
Their girl is very good at sports.
'Girl' here means a female who is a person’s romantic partner. It is a casual way to say girlfriend. Usually young women are called girls this way.
Tom said his girl is coming today.
She took her girl to the movie.
In older or informal English, 'girl' can mean a female employee. For example, a salesgirl or waitress. It is less common now and sometimes sounds old-fashioned.
She is a sales girl in the shop.
The coffee shop hired two girl waiters.
'Girls' can mean a group of females or women in informal speech. It is often used among women or for friendly conversation. It does not always mean children.
The girls are meeting after school.
The girls went shopping together.
'Girl' is used in idioms or phrases to show female strength or identity, like 'girl power.' Here it means women or females in general, often positively.
The girls can do anything they want.
Girl power means strong women together.