The G flat minor seventh chord is a 4-note chord consisting of the notes Gb, Bbb, Db and Fb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Gbm7.
Chords that are a superset of Gbm7. The chords include more notes but always Gb, Bbb, Db and Fb.
Chords that are a subset of Gbm7. These contain less notes but all of them are included in Gbm7.
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 Gbm7 chord. Feel free to save or share the image as needed.