User Visibility & Management enables you to determine if team members can see other users within the team and invite new users to join your team:
To allow team members to see other users within the team, select the check box for Allow users to see other users on team plan.
To enable members of your team to invite other users to your Team Plan, select Allow users to invite other users to the plan. When you select this option you can also decide whether to automatically add users that your team members invite, or require the approval of a Team Admin before adding them.