The collective nouns they are singular words that refer to a set, or a type of objects that exist together and are considered as a single unit. They represent the notion of plurality.
Examples of collective nouns in English:
Alphabet
Army (Army = set of soldiers)
Band (Band = set of musicians)
Bevy (= Herd)
Block (block = set of houses)
Delete (board = set of people who make a decision in a company)
Bouquet (Bouquet = flower set)
Brotherhood (Brotherhood, brotherhood = set of priests or monks)
Bunch (bunch = bunch of grapes)
Buttery (Pantry = food set)
Caravan (caravan = set of travelers traveling by land)
Catalog (Catalog = set of images or product announcements)
Cavalry (Cavalry = set of soldiers on horseback)
Cementery (Cemetery = Set of graves)
Census (Register = set of registered voters; in this case the s is not plural)