of
In Italian, the word 'di' is used to express possession, association, or relationship between two nouns, similar to 'of' in English. It is also used to express the origin or source of something, such as 'di Roma' (of Rome).
Marco's book is interesting.
This phrase indicates that the book belongs to Marco, using 'di' to show possession.
Giulia's house is big.
In this sentence, 'di' is used to express that the house belongs to Giulia, highlighting a relationship of ownership.
Paolo's work is difficult.
Here, 'di' shows that the work is associated with Paolo, indicating that it is his work.