The A minor sixth chord is a 4-note chord consisting of the notes A, C, E and F#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Am6.
Chords that are a superset of Am6. The chords include more notes but always A, C, E and F#.
Chords that are a subset of Am6. These contain less notes but all of them are included in Am6.
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 Am6 chord. Feel free to save or share the image as needed.