8 NaNO3 (aq) + 3 Cu (s) + 4 H2SO4 (aq) → 3 Cu(NO3)2 (aq) + 4 Na2SO4 (aq) + 2 NO (g) + 4 H2O (l)
This is an oxidation-reduction (redox) reaction:
3 Cu0 - 6 e- → 3 CuII (oxidation)
2 NV + 6 e- → 2 NII (reduction)
Cu is a reducing agent, NaNO3 is an oxidizing agent.