The A flat fifth chord is a 2-note chord consisting of the notes Ab and Eb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Ab5.
Chords that are a superset of Ab5. The chords include more notes but always Ab and Eb.
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 Ab5 chord. Feel free to save or share the image as needed.