We all have roles that we play. No, not in roles in a "play", but roles we play in life. To a psychologist, a role is a set of expectations about the ways in which people are supposed to behave in different situations. Roles are dependent on all sorts of things like the position a person holds, the culture, etc. For example, a person who is the CEO of a company is expected to act in certain ways specifically because of the title the person holds and the expectations we have in our society about the ways CEOs should behave.