This app helps you to find out which strings and fret position can be used for the notes in the new score you are going to learn. Placing some notes on the score, their positions are shown on the guitar view. Also, you can hear each note.
You might think it is much easier and faster using your guitar to find out the position.
Mmm, I agree if I am a good player. But there may be some other positions I did not find out.