There is no sound [v] in Spanish. Both letters B (be) and V (uve) represent the same bilabial sound [b]. This fact tends to arouse confusion and even mistrust, however, believe us, it’s true. Moreover, the Spanish themselves cannot distinguish by ear the bilabial [b] and dentilabial [v]. If they don’t know the spelling, the ask:
¿Se escribe con be o con uve? – Is it spelt with “b” or “v”?
The letter n before b, v sounds like [m]:
Un beso [umbeso]
Convertir [combertir]