4 Cu2IO + 18 HNVO3 N2IO + 8 CuII(NVO3)2 + 9 H2O

This is an oxidation-reduction (redox) reaction:

8 CuI - 8 e- 8 CuII (oxidation)

2 NV + 8 e- 2 NI (reduction)

Change the oxidation states