We use it:
For something that started in the past and continues in the present:
We have lived in London for 10 years.
Are we living in London right now?
When did we move to London?
We use it:
For actions performed in unfinished periods of time.
She has watched that movie three times this week.
Is this week finished?
Is she watching the movie right now?
have/has + past participle
The difference is where the person is at the moment of speaking.
The have been to Paris.
They have gone to Paris.
Where are they?
We’ve been to Argentina.
We don’t know, but they are not in Argentina.
She’s gone to Mexico.
She is in Mexico.