Bb maj11/F
The Bb maj11 chord consists of the Bb (Perfect unison), D (Major third), F (Perfect fifth), A (Major seventh), C (Major ninth) and Eb (Perfect eleventh) notes, with F as the bass note.

How to play the Bb maj11/F chord
- Play F as the lowest bass note in the left hand
- 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
- Add C (Major ninth) — 14 semitones above Bb
- Add Eb (Perfect eleventh) — 17 semitones above Bb
- Press all 7 notes simultaneously to sound the Bb maj11/F chord