roof
The word 'tetto' is used in Italian to refer to the top covering of a building or vehicle. It can also be used metaphorically to refer to a limit or ceiling. For example, 'Il tetto del mio appartamento è stato danneggiato dal vento' means 'The roof of my apartment was damaged by the wind'.
The roof of our house is red.
This sentence describes a characteristic (color) of a specific object (the roof of our house). 'Tetto' is used in its core sense: the uppermost part of a house that is constructed to provide shelter from the elements.
I have a book on the roof.
This sentence tells about the location of a book, indicating that it's located on the roof, possibly forgotten there or placed for some other reason. It's an unusual phrase, implying a potentially interesting story behind it.
The protective roof is essential on a construction site.
The sentence expresses the importance of safety measures ('protective roof') in certain environments ('construction site'). It shows the word 'tetto' in a context which refers to a structure for protection rather than part of a house.