Pronunciation exercises: /b/ vs /v/

/b/ is a bilabial voiced phoneme. /v/ is a labiodental voiced phoneme. The difference between /b/ and /v/ is the same as the difference between /p/ and /f/ (voiceless counterparts).

Minimal pairs
There are very few minimal pairs contrasting /b/ and /v/
 * ban - van; berry, burry - very; best - vest; bet - vet; boat - vote; curb (v., n.), kerb (n.) - curve; Serb - serve