A person can have multiple roles within a league.
For example, a person could be a Player on 1 or more teams, a Team Administrator for 1 or more teams and be both a Player and Team Administrator on a team.
If a person has login access to a league they will only be able to access certain sections based on their role.
To view and edit security options for a particular role:
Go to Setup > Settings > Roles (tab)
Then click 'Override' - next to the role to see what access they have to the admin pages.
If you have already changed the security settings for a role, then click 'Edit'.