It can also be used more colloquially to refer to:
* A guy, a dude, a man: This is more common in informal contexts, especially among younger people.
* A friend: This usage is more common in some regions of Latin America.
So, depending on the context, "un tio" could be translated as:
* An uncle
* A guy
* A dude
* A man
* A friend
It's important to consider the surrounding context to understand the intended meaning of "un tio."