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 structure rooted off the 2nd fret of the 5th string. The 2nd string open is a B which is the root in the key of B. The 1st string open is an E which is the 4 in the key of B. The total formula of this voicing is 1 4 5 therefore it is a Bsus4. The formula 1 4 5 is a subset of the following scales: ionian, dorian, phrygian, mixolydian, aeolian, melodic minor, mixolydian b6, phrygian dominant. The included chart shows this chord/scale relationship for the sus4 harmony.