B 5/A
The B 5 chord consists of the B (Perfect unison) and F# (Perfect fifth) notes, with A as the bass note.

How to play the B 5/A chord
- Play A as the lowest bass note in the left hand
- Find B (Root) on the piano keyboard
- Add F# (Perfect fifth) — 7 semitones above B
- Press all 3 notes simultaneously to sound the B 5/A chord