The B minor/major ninth chord is a 5-note chord consisting of the notes B, D, F#, A# and C#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as BmM9.
Interactive piano diagram for the B minor/major ninth chord
Chords that are a subset of BmM9. These contain less notes but all of them are included in BmM9.