KBrO3 (aq) + 6 NaCl (aq) + 3 H2SO4 (aq) → 3 Cl2 (g) + KBr (aq) + 3 Na2SO4 (aq) + 3 H2O (l)
This is an oxidation-reduction (redox) reaction:
BrV + 6 e- → Br-I (reduction)
6 Cl-I - 6 e- → 6 Cl0 (oxidation)
KBrO3 is an oxidizing agent, NaCl is a reducing agent.
This is a gas evolution reaction, Cl2 is the formed gas.