4 NaOH + 3 Ag2O + 2 Cr(OH)3 → 5 H2O + 2 Na2CrO4 + 6 Ag
This is an acid-base reaction (neutralization): NaOH is a base, Cr(OH)3 is an acid.
This is an oxidation-reduction (redox) reaction:
6 AgI + 6 e- → 6 Ag0 (reduction)
2 CrIII - 6 e- → 2 CrVI (oxidation)
Ag2O is an oxidizing agent, Cr(OH)3 is a reducing agent.