Fe2IIS2-II + 8 HNVO3 Fe2III(NIVO3)3 + 2 H2SVIO4 + 5 NIIO + 2 H2O

This is an oxidation-reduction (redox) reaction:

2 S-II - 16 e- 2 SVI (oxidation)

5 NV + 15 e- 5 NII (reduction)

3 NV + 3 e- 3 NIV (reduction)

2 FeII - 2 e- 2 FeIII (oxidation)

Change the oxidation states