Ab sus4/C
The Ab sus4 chord consists of the Ab (Perfect unison), Db (Perfect fourth) and Eb (Perfect fifth) notes, with C as the bass note.

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