The term agent can have different meanings considering the theoric field in which the concept is inserted. Generally, the term agent is used to describe a person who can manage their actions in a result/goal-oriented manner or a person who performs on behalf of another individual or organization.
In social psychology, the concept of the agent was popularized by Albert Bandura’s social theory of human agency, according to which to be an agent is to have the capacity to intentionally behave in a matter that influences one’s functioning and contextual circumstances. In other words, an agent is a person capable of affecting a course of events through his actions, which include interacting with others or with elements of the context, engaging in reflection, using strategies, generating plans and predicting results.
For example, an agent may be someone who strikes up a conversation with another, a student who studies for an exam, or a counselor who helps their clients.