The D flat major ninth chord is a 5-note chord consisting of the notes Db, F, Ab, C and Eb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dbmaj9.
Chords that are a superset of Dbmaj9. The chords include more notes but always Db, F, Ab, C and Eb.
Chords that are a subset of Dbmaj9. These contain less notes but all of them are included in Dbmaj9.
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 Dbmaj9 chord. Feel free to save or share the image as needed.