piano chord
D♭6
D♭1F3A♭5B♭6
A major triad with a sixth added. The same four notes as a minor seventh chord a third below.
Written the other way round it is C♯6 — the same twelve keys on a piano, a different piece of notation.
What is true of it
D♭6 is D♭, F, A♭ and B♭ — 1, 3, 5 and 6 counted from D♭.
These are also the notes of B♭m7/D♭ and A♯m7/D♭. Which name is right depends on what is underneath and what came before — the notes alone do not decide.
On an instrument that cannot reach all 4, the 5 goes first, in that order.