3 Au0 + 2 HNVO3 + 9 HCl 3 HAuIICl3 + 2 NIIO + 4 H2O

This is an oxidation-reduction (redox) reaction:

3 Au0 - 6 e- 3 AuII (oxidation)

2 NV + 6 e- 2 NII (reduction)

Change the oxidation states