The A major thirteenth chord is a 6-note chord consisting of the notes A, C#, E, G#, B and F#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Amaj13.
Interactive piano diagram for the A major thirteenth chord
Chords that are a subset of Amaj13. These contain less notes but all of them are included in Amaj13.