VOICED BILABIAL STOP [b]
VOICED LABIODENTAL FRICATIVE [v]
Be with dagesh is pronounced like English "b". Be with rafe, which typically occurs after vowels, is pronounced like English "v".
SOURCES AND FURTHER READING
Khan, Geoffrey. 2020. The Tiberian Pronunciation Tradition of Biblical Hebrew. Cambridge: Cambridge and Open Book Publishers. §I.1.2.