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

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