uncle
The word 'zio' is used in Italian to refer to an uncle. This can be a brother of one's parent or the husband of one's aunt. It is a common term in family vocabulary and is used in the same way as in English.
My uncle lives in Rome.
This sentence is a simple introduction of a family member, using the term 'zio' for uncle and asserting his place of residence.
Uncle, could you pass me the salt please?
In this instance, 'zio' is used directly to address a person, this same construct applies when asking for something from someone in Italian, in this case, the salt.
I haven't seen my uncle for a long time.
This sentence uses 'zio' in a familial context, indicating a period of absence. This is a common phrase to express the elapsed time since the speaker has seen a person.