The Word is:”of”
1. expressing the relationship between a part and a whole:
“the sleeve of his coat”
“nine of the children came to the show”
2. expressing the relationship between a scale or measure and a value.
“an increase of 5%”
“a boy of 15”
3. indicating an association between two entities, typically one of belonging, in which the first is the head of the phrase and the second is something associated with it.
“the son of a friend”
“the plays of Shakespeare”
4. expressing the relationship between a direction and a point of reference.
“north of Watford”
5. expressing the relationship between a general category or type and the thing being specified which belongs to such a category.
“the city of Prague”
6.expressing the relationship between an abstract concept having a verb-like meaning and a noun denoting the subject of the underlying verb.
“the opinion of the directors”
“the murder of two boys”
“it was kind of you to ask”
7. indicating the relationship between a verb and an indirect object:
“I don’t know of anything that would be suitable”
“he died of cancer”
8. indicating the material or substance constituting something.
“the house was built of bricks”
expressing time in relation to the following hour.
“it would be just a quarter of three in New York”
Source credit: Google