Barre chord
fret 2, A shapex24432
Bm is the B minor chord. Its notes are B, D and F♯. The lowered third gives this triad its darker color.
x24432
799777
Numbers show frets from the low E string to the high e string; x means don't play that string.
Bm is the ii chord in A major, the iii chord in G major and the vi chord in D major. That makes it a natural fit in songs written in those keys.
Every B, D and F♯ on the first 12 frets. The filled dots are the root, B. Build your own shape from any nearby group.
Other B chords
Other minor chords