piano chord
Dm6
D1F♭3A5B6
A minor triad with a major sixth added, which is why it is not simply a minor chord with a flat seventh.
What is true of it
Dm6 is D, F, A and B — 1, b3, 5 and 6 counted from D.
These are also the notes of Bm7♭5/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.