Question

b English back, cab. Spanish b and v, as in beso or vaso, as long as it comes after a nasal consonant or the beginning of a sound group, otherwise b and v are always fricatives [β].

Accepted Answer

Voiced Bilabial Plosive http://en.wikipedia.org/wiki/Voiced_bilabial_plosive

Symbol	b
Name	Voiced Bilabial Plosive
Notes	English back, cab. Spanish b and v, as in beso or vaso, as long as it comes after a nasal consonant or the beginning of a sound group, otherwise b and v are always fricatives [β].
Ref	http://en.wikipedia.org/wiki/Voiced_bilabial_plosive

B V Voiced Bilabial Plosive English Ack Ca