The A flat sixth chord is a 4-note chord consisting of the notes Ab, C, Eb and F.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Ab6.
Chords that are a superset of Ab6. The chords include more notes but always Ab, C, Eb and F.
Chords that are a subset of Ab6. These contain less notes but all of them are included in Ab6.
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 Ab6 chord. Feel free to save or share the image as needed.