Collective nouns as singular or plural?

[Aikuzo3]

Quote:

"Collective nouns are sometimes counted as one unit (that is, considered to be singular) and sometimes counted separately (that is, considered to be plural). Army, herd, pack, and family are all collective nouns."

Can someone explain what "counted separately" means. Can I have examples of collective nouns that are singular and plural.

 

[Rover_KE]

In this list of collective nouns I'd say that most, if not all of them can be used in both the singular and plural.

Rover