3 CuS-II + 8 HNVO3 3 CuSVIO4 + 8 NIIO + 4 H2O

This is an oxidation-reduction (redox) reaction:

3 S-II - 24 e- 3 SVI (oxidation)

8 NV + 24 e- 8 NII (reduction)

CuS is a reducing agent, HNO3 is an oxidizing agent.