A manager is someone who leads his team and developes them in the way he wants them to go to achieve targets. So one of his main skills is that of being a motivator and team leader.
Staff are motivated in different ways; with some its money, with others its doing a good job he is proud of. Your job as a manager is to identify what makes each employee tick and work with those assets. For some reason, giving bonuses in response to achieving a target is a popular British management trait, but the guys who are money driven could end up taking short cuts and not cleaning properly just to learn the money. The end result is that your business reputation suffers. The guys who aren't money driven just become demotivated and produce less.
I watched several really good salemen in the Reg Vardy car dealerships being promoted to sales managers. When asked what their key function was, several replied that it was to hire and fire. There was no consideration on their part that one of their key responsibilities was to train and 'groom' their staff in the way that would get the best out of their selling skills to sell more cars.