El tío means "uncle" in Spanish. Just like your real uncle, el tío can be a loving family member who tells you stories and jokes, or a more distant relative whom you don't see very often.
But in some Latin American cultures, el tío can also be a scary figure. People believe he lives in mines or caves and is able to control the elements of earth and water. Some people even offer him gifts and sacrifices so he won't cause harm or illness.
The belief in el tío is linked to traditional mining practices and the dangers that miners face. It's a way to explain accidents or illnesses that happen in the mines.
So, to sum it up, el tío can be either a friendly family member or a scary mythological figure, depending on the context and culture.