Signs on	-	When a member of your buddy list signs on a popup notification is shown.
Signs off	-	As above but happens when buddy signs off.
Goes away	-	As above but happens when a buddy goes away.
Comes back from away	-	As above but happens when a buddy comes back from away.
Replace alert windows with a notification	-	With this option enabled a popup notification will occur instead of a window being shown when an alert is set on a buddy.
Disable notifications while away	-	Enable this option if you don't want notifications to be shown while you are away.
Display notifications for x seconds	-	Set the time that popup notifications are shown for.