CuS-II + 4 HNVO3 Cu(NVO3)2 + SIVO2 + 2 NIIO + 2 H2O

This is an oxidation-reduction (redox) reaction:

S-II - 6 e- SIV (oxidation)

2 NV + 6 e- 2 NII (reduction)

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