BSON, as name sound?s, it is short name of Binary JSON. BSON is binary serialized JSON like objects. BSON is just like JSON which supports array and array of other objects.
There is one difference between JSON and BSON is that BSON supports some data type information also.
BSON is designed by keeping these things in mind.
Data representation should be lightweight for network uses.
BSON is designed to be traversed easily. Like JSON.
Encoding data to BSON and decoding from BSON can be performed very quickly in most languages due to the use of C data types.
For more info please see http://bsonspec.org