Collective nouns are those that are made up of a number of individuals. The verb can be used in both single and plural depending on whether you are referring to the noun as a whole or as a group of individuals.
My family are all doctors- En mi familia somos todos médicos
My family is big- Mi familia es grande
The team is very good- El equipo es muy bueno
The team are playing badly- El equipo está jugando mal.
Examples of collective nouns are: group, family, team, government, company, band, majority, class, public