The A flat major ninth chord is a 5-note chord consisting of the notes Ab, C, Eb, G and Bb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Abmaj9.
Chords that are a superset of Abmaj9. The chords include more notes but always Ab, C, Eb, G and Bb.
Chords that are a subset of Abmaj9. These contain less notes but all of them are included in Abmaj9.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Abmaj9 chord. Feel free to save or share the image as needed.