× = don't play that string, ○ = open string. Numbers next to a diagram give the fret it starts on.
See every G♭m7 note on the neckG♭m7 is one of the seven chords in: D major (iii7), B minor (v7), A major (vi7), F♯ minor (i7), E major (ii7), C♯ minor (iv7).