9 NaNVO3 + 4 NaOH + Cr2IIIO3 2 Na2CrXIIO7 + 9 NaNIIIO2 + 2 H2O

This is an oxidation-reduction (redox) reaction:

9 NV + 18 e- 9 NIII (reduction)

2 CrIII - 18 e- 2 CrXII (oxidation)

Change the oxidation states