2 Cr(OH)3 + 3 Br2 + 10 NaOH → 2 Na2CrO4 + 6 NaBr + 8 H2O
This is an acid-base reaction (neutralization): Cr(OH)3 is an acid, NaOH is a base.
This is an oxidation-reduction (redox) reaction:
6 Br0 + 6 e- → 6 Br-I (reduction)
2 CrIII - 6 e- → 2 CrVI (oxidation)
Br2 is an oxidizing agent, Cr(OH)3 is a reducing agent.