Its literal meaning in Japanese is 'boy love'. In Japan, it's associated with paedophilia and is an obsolete term. In the West, however, it's taken on new meaning to refer to the less graphic depictions of male/male romantic relationships aimed at women. More descriptive art and fiction are often referred to as yaoi
. Female/female relationships are called either shoujoai
, depending on how graphic they are.
Many people have different attitudes to its use. Others will demand you use the term BL/boy's love as they do in Japan, some will say it covers all m/m relationships, but most follow the above description.