Bb maj7
The Bb maj7 chord consists of the Bb (Perfect unison), D (Major third), F (Perfect fifth) and A (Major seventh) notes.

How to play the Bb maj7 chord
- Find Bb (Root) on the piano keyboard
- Add D (Major third) — 4 semitones above Bb
- Add F (Perfect fifth) — 7 semitones above Bb
- Add A (Major seventh) — 11 semitones above Bb
- Press all 4 notes simultaneously to sound the Bb maj7 chord