10 Fe0 + 36 HNVO3 10 FeIII(NVO3)3 + 3 N20 + 18 H2O

This is an oxidation-reduction (redox) reaction:

6 NV + 30 e- 6 N0 (reduction)

10 Fe0 - 30 e- 10 FeIII (oxidation)

Change the oxidation states