Cr0 + 3 NaNVO3 + 2 NaOH 3 NaNIIIO2 + Na2CrVIO4 + H2O

This is an oxidation-reduction (redox) reaction:

3 NV + 6 e- 3 NIII (reduction)

Cr0 - 6 e- CrVI (oxidation)

NaNO3 is an oxidizing agent, Cr is a reducing agent.