The D flat minor ninth chord is a 5-note chord consisting of the notes Db, Fb, Ab, Cb and Eb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dbm9.
Chords that are a superset of Dbm9. The chords include more notes but always Db, Fb, Ab, Cb and Eb.
Chords that are a subset of Dbm9. These contain less notes but all of them are included in Dbm9.
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 Dbm9 chord. Feel free to save or share the image as needed.