The user details tab holds detailed information about the user. For example their role, department, location, assigned Microsoft licensens etc.
It's also the place where you can link through to the User Details page for additional analytics, as to the users direct manager.
The TrueDEM License visible here determines which data is collected for the user in TrueDEM and whether or not data like Teams Call analysis are available. More information on the licenses and roles can be found here: TrueDEM App Roles