These settings are used for the visual alarm clock. This alarm clock can be displayed by choosing 'alarm clock' from the 'window' menu in the main window. The alarm clock can also be used as an alarm action.
Stop alarm clock action after ... minutes
Specifies when the alarm clock should be stopped ringing.
Snooze time ... minutes
Specifies after how long the alarm clock should ring again when it was set to snooze (by clicking the alarm clock window). This snooze is completely different from the snoozing of alarms.