In linguistics, a collective noun is a word referring to a collection of things taken as a whole. Most collective nouns in everyday speech are not specific to one kind of thing. For example, the collective noun "group" can be applied to people ("a group of people"), or dogs ("a group of dogs"), or objects ("a group of stones"). Although syntactically the collective noun can be "singular", it's still semantically a collection of entities.
Some collective nouns are specific to one kind of thing, especially terms of venery, which identify groups of specific animals. For example, "pride" as a term of venery always refers to lions, never to dogs or cows. Other examples come from popular culture such as a group of owls, which is called a "parliament".