2 KNVO3 + Cr2IIIO3 + 2 KOH 2 KCrVO3 + 2 KNIIIO2 + H2O

This is an oxidation-reduction (redox) reaction:

2 NV + 4 e- 2 NIII (reduction)

2 CrIII - 4 e- 2 CrV (oxidation)

Change the oxidation states