3 Cu2S-II + 14 HNVO3 6 CuNVO3 + 8 NIIO + 3 H2SVIO4 + 4 H2O

This is an oxidation-reduction (redox) reaction:

3 S-II - 24 e- 3 SVI (oxidation)

8 NV + 24 e- 8 NII (reduction)

Change the oxidation states