3 CuIIS-II + 4 HNVO3 3 CuINVO3 + 3 S0 + NIIO + 2 H2O

This is an oxidation-reduction (redox) reaction:

3 CuII + 3 e- 3 CuI (reduction)

3 S-II - 6 e- 3 S0 (oxidation)

NV + 3 e- NII (reduction)

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