2 MnCl2 (aq) + 16 NaOH (aq) + 5 Cl2 (g) → 2 NaMnO4 (aq) + 14 NaCl (aq) + 8 H2O (l)
This is an oxidation-reduction (redox) reaction:
2 MnII - 10 e- → 2 MnVII (oxidation)
10 Cl0 + 10 e- → 10 Cl-I (reduction)
MnCl2 is a reducing agent, Cl2 is an oxidizing agent.