The G flat minor ninth chord is a 5-note chord consisting of the notes Gb, Bbb, Db, Fb and Ab.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Gbm9.
Chords that are a superset of Gbm9. The chords include more notes but always Gb, Bbb, Db, Fb and Ab.
Chords that are a subset of Gbm9. These contain less notes but all of them are included in Gbm9.
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 Gbm9 chord. Feel free to save or share the image as needed.