A purpose is an inspiring reason that explains why we do what we do and how we do it.
In a workplace guided by purpose, you will find purpose at the levels of:
the organization, i.e. the big WHY this organization exists in the first place,
the teams or circles, i.e. why this group of things need to get done,
the roles, i.e. why this particular role needs to exist, and
the individual, i.e. the people who put energy into these roles, who also have personal dreams, purpose and ambitions.
In a self-managed organization, the Purpose orients the action of a Role even if any other explicit Accountabilities, Policies, Strategies, Priorities, or resources have not been defined.
As explained by Simon Sinek in his popular book Start with WHY, when an organization has a clear Purpose, it because responsive and antifragile because its Purpose helps the organization navigate unexpected obstacles or evolutions, like the North Star guides the lost traveler.