Scaler 2 has a 46 page manual, but really doesn’t elaborate on the guitar fretboard display. I suspect this is visualization intended to be intuitive. But as we all know, nothing is obvious to the uninformed.
Looks to me like the fretboard has “bolded” all the notes of the C-Major scale and then shaded the C Major triad (the 1st, 3rd and 5th of the scale). That is the C, E, G. The post script # identifies the pitch of the root note, C which corresponds to the position of the piano keyboard.
You need to experiment with more complex chords to see how the program displays chord/scale extensions beyond the triad. And one final tip from an old Guitar player, learn the notes of the fretboard as a priority! It will help with everything down the road.