Group Permissions and User Permissions have slightly different header fields. Both types are explained here.

Group Permissions Header Fields

Header Fields for Group edit or create
Zones:  The list of zone name(s) identified for the selected Permissions Group.
Users:  The list of users identified in this Permissions Group.
Sub-Groups:  The list of other Permissions Group(s) identified as part of this Permissions Group.

User Permissions Header Field

When you edit user permissions directly in the Advanced User Permission view, the following warning will appear:

User permission warning
Advanced User Permission Headers
Allowed Zones:  The list of zone name(s) the selected user has permission to access.