his
The word 'suo' is the Italian equivalent of the English possessive pronoun 'his'. It is used to indicate that something belongs to a male person or animal. For example, 'Il suo libro' means 'His book'. It is important to note that in Italian, the possessive adjective must agree in gender and number with the object it refers to, not the owner. So, 'sua' is used for feminine singular nouns, 'suoi' for masculine plural nouns, and 'sue' for feminine plural nouns.
His book is very interesting.
This phrase expresses that a book belonging to a male person is interesting.
I saw his dog in the park.
In this sentence, it is indicated that a dog that belongs to a male individual was seen in the park.
His car is new.
This statement points out that a car, which belongs to a male person, is new.