piano chord
Gm6
G1B♭♭3D5E6
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
Gm6 is G, B♭, D and E — 1, b3, 5 and 6 counted from G.
These are also the notes of Em7♭5/G. 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.