Bb sus4/Cb
The Bb sus4 chord consists of the Bb (Perfect unison), Eb (Perfect fourth) and F (Perfect fifth) notes, with Cb as the bass note.

How to play the Bb sus4/Cb chord
- Play Cb as the lowest bass note in the left hand
- Find Bb (Root) on the piano keyboard
- Add Eb (Perfect fourth) — 5 semitones above Bb
- Add F (Perfect fifth) — 7 semitones above Bb
- Press all 4 notes simultaneously to sound the Bb sus4/Cb chord