Watch the 1 5 1 Structures online guitar lesson by Brad Carlton from Guitar Lab: Open String Universe
This chord is A root 5th root structured rooted off the 10th fret of the 5th string. The 2nd string open is a B which is the 3 in the key of G. The 1st string open is an E which is the 6 in the key of G. The total formula of this voicing is 1 3 5 6 therefore it is an G6. The formula 1 3 5 6 is a subset of the following scales: ionian, lydian, mixolydian, overtone, half-whole diminished. The included chart shows this chord/scale relationship for the 6 harmony.