A football manager is responsible for running a football club or national team, often including coaching the players and hiring the other backroom staff. A club manager is responsible directly to the club chairman, whereas a national team manager reports to the head of the Football Association of that country.
In Football Manager, this is you! The term is also used to refer to the other human or NPC managers of other clubs and nations within the game.
The roles and responsibilities of a football manager vary greatly throughout the world. For example, in English football the manager is responsible for almost everything on the pitch, from training to tactics to player selection to club discipline, as well as the buying and selling of players. In other parts of the world, such as Spain, the manager is really more of a head coach and he rarely has control of player transfers and contracts, focussing almost solely on team selection, training and tactics.
In Football Manager, the manager's duties are based on the English style of management although, in recent versions, we have seen the addition of new staff roles like Director of Football and Head of Youth Development which allows the manager to delegate some duties to his colleagues.