A /purpose/ sets the vision that aligns and motivates a team to create high quality outcomes. It defines the /what/ and /why/ for the team.
If team members are unaware or not bought into the purpose they can end up undermining outcomes by doing the wrong work.
A manager’s first big task is to “ensure that [their] team knows what success looks like and cares about achieving it.”
For example, let's say your vision is to get a lemonade stand on every block, starting first in your city and then expanding throughout the country. However, your employee Henry is under the impression that your stand ought to be a popular hangout spot for the neighbors. He'll start doing things that you think are unimportant or wasteful, like buying a bunch of lawn chairs or trying to serve pizza along with lemonade. To prevent these misalignments, you ll need to get him and the other members of your team on board with what you truly care about. Julie Zhou, The Making of a Manager