You may run Security()->showUserLevelInfo() in any page and check the info shown in the Debug bar. (Make sure you enable Debug first.) You’ll see info like:
AdvancedSecurity::UserLevel: ...
AdvancedSecurity::UserLevelPriv: ...
AdvancedSecurity::currentUserLevelID(): ...
AdvancedSecurity::userLevelList(): ...
The AdvancedSecurity::userLevelList() should show all the user levels that the user has.