Present Perfect describes an action or situation that started in the past and continues in the present.
I have lived in Bristol since 1984.
Present Perfect is used to say that an action happened at an unspecified time before now. The exact time is not important.
What else has she told you?
Present Perfect is used to express an action that was completed in the very recent past, expressed by ‘just’.
I have just finished my work.
Present Perfect is used to describe experience.
You have seen many things.