piano chord
B♭m7
B♭1D♭♭3F5A♭♭7
Minor triad with a minor seventh. The same four notes as a major sixth chord a third above.
Written the other way round it is A♯m7 — the same twelve keys on a piano, a different piece of notation.
What is true of it
B♭m7 is B♭, D♭, F and A♭ — 1, b3, 5 and b7 counted from B♭.
These are also the notes of D♭6/B♭ and C♯6/B♭. 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.