...So, if for example you do 30 reps in one minute, that means 1 rep every 2 secs.
The software calculates that and gives you the "beep" every 2 secs.
It is useful for frequencies like 2,5, 1,7 secs, etc. You will have the rythm wihtout bothering to guess it.
A good application is the lactate tolerance improvement of aerobic exercises like rowing, biking, running, kettlebell snatching, etc.