Some call this the “Hendrix” chord because he used often and inspired so many others to use it. It’s the 7#9 with the root on the 5th string. So on the 7th fret it would be E7#9. It’s a basic B7 shape in the first position but the note on the 2nd string gets moved up 1/2 step (sharpened). Typically played as the V chord in a I. IV, V blues progression, the 7#9 played as the last chord in the turnaround just before returning to the top gives it some nice tension. Also sounds nice as an arpeggio.
E7#9 = X7678X, B7#9 = X2123X. Have fun!
D5