b and v are very similar, they almost sound the same.

hola Junior el sonido de la letra "v " y la "b" es igual, la b es enteramente labial, mientras que la v es labiodental, se deben considerar algunas normas de ortografía para la correcta escritura de las palabras con estas letras sonia

Hola Junior, Both the 'b' and the 'v' are pronounced alike in Spanish. Their place in the word will cause their pronunciation to vary a little. You can check for more details here: http://spanish.about.com/od/spanishpronunciation/a/b.htm