Short Rest detection is a function in the goggles that allows the classification of brief rest moments between fast swimming intervals. This is likely necessary for competitive level swimmers but is not usually needed for the average swimmer.  

Example: Swimming 100m intervals, completing them in 1 minute and 24 seconds with the next take off time set for 1 minute and 30 secs. The goggles will be identifying those 6 seconds difference as rest before starting the next interval.

This setting can be toggled on and off in the settings of the profile tab of the app.