Other contributors have said "What does 3 equals bm?" is the same question as "What is BM?" If you believe that these are not asking the same thing and should be answered differently, click here
Usually when people talk about a BM, they mean a "bowel movement" (aka defecation) or if they leave out the word "a" and just talk about "BM", then they may be referring to the fecal material or poop.
bowel movement, if one is using medical terms. Since I arrived here from a question posted at the end of an article on Bank Hapoalim B.M., I assume that the question relates to Israeli companies...