The A flat minor/major ninth chord is a 5-note chord consisting of the notes Ab, Cb, Eb, G and Bb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as AbmM9.
Interactive piano diagram for the A flat minor/major ninth chord
Chords that are a subset of AbmM9. These contain less notes but all of them are included in AbmM9.