The G flat fifth chord is a 2-note chord consisting of the notes Gb and Db.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Gb5.
Chords that are a superset of Gb5. The chords include more notes but always Gb and Db.
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 Gb5 chord. Feel free to save or share the image as needed.