The term collective nouns refers to a noun which is refers to a group of nouns. The nouns can be people, places or things. Some collective nouns are non-specific and can refer to any noun (e.g. group: group of people, group of photographs, group of chairs), and some can refer to only one thing (e.g. a pride of lions; you can’t have a pride of chairs or a pride of birds).
Hand me that bouquet of flowers, please.
The teacher brought in a bunch of books for us to look at.
The grandmother fed her grandson a whole pile of cookies.
The collective noun may mean something entirely different when used as a common noun:
There’s a murder of crows in that field.
Have a look at that school of fish.
Alex walked right into a bed of snakes.
Generally, collective nouns are followed by of: e.g. a herd of cows. Sometimes, though, we get lazy and leave out the of ___. For instance, we would usually just say an audience because we know that an audience is comprised of people (not too many Martians in an audience, one hopes).
We will side with the majority (of voters).
Please hand these papers out to the class (of students).
In formal writing, collective nouns can be replaced by a singular pronoun.
The herd is going to the watering hole.
The herd are going to the watering hole.