Now close the User dialog and go to Roles. Open the corresponding Role to see the permissions. Red flags mean the permission for this item is not enabled (off); green flags mean the permission is enabled (on).
Roles are cumulative, meaning that if a User has both the "User" and "Sales Rep" Roles, they will have the combined permissions for each Role... Be sure to check each Role assigned to a User to get a correct understanding of what permissions that User has.
In general, all regular Users will has the "User" Role as this is the base permission to access most basic functions of the system, like contacts, calendars, etc.