3 CuIIO + 2 N-IIIH3 3 Cu0 + N20 + 3 H2O

This is an acid-base reaction (neutralization): CuO is an acid, NH3 is a base.

This is an oxidation-reduction (redox) reaction:

3 CuII + 6 e- 3 Cu0 (reduction)

2 N-III - 6 e- 2 N0 (oxidation)

Change the oxidation states