Allow applications and services to prevent automatic sleep. If you enable this policy setting, any application, service or ...

Allow applications and services to prevent automatic sleep.
      
If you enable this policy setting, any application, service or device driver may prevent Windows from automatically transitioning to sleep after a period of user inactivity.

If you disable this policy setting, applications, services or drivers may not prevent Windows from automatically transitioning to sleep.  Only user input will be used to determine if Windows should automatically sleep.