The /v/ sound is spelled with <v>, while the /j/ sound is spelled <y>. The contrast only occurs initially.
The contrast is between a labio-dental fricative and a palatal semivowel. It causes no problems.
V ye vac yak vacs yaks vale Yale vales Yales veil Yale veils Yales veer year veers years vend yenned vet yet vocal yokel vocals yokels