2 HN3 + CuO → 3 N2 + Cu + H2O
This is an acid-base reaction (neutralization): HN3 is an acid, CuO is a base.
This is an oxidation-reduction (redox) reaction:
CuII + 2 e- → Cu0 (reduction)
6 N-1/3 - 2 e- → 6 N0 (oxidation)
CuO is an oxidizing agent, HN3 is a reducing agent.