Cu⁰ + 2 HN^VO₃ + 2 HCl → Cu^IICl₂ + 2 N^IVO₂ + 2 H₂O

This is an oxidation-reduction (redox) reaction:

Cu⁰ - 2 e^- → Cu^II (oxidation)

2 N^V + 2 e^- → 2 N^IV (reduction)

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