This is an oxidation-reduction (redox) reaction:
12 Br-I - 12 e- → 12 Br0 (oxidation)
2 BrVI + 12 e- → 2 Br0 (reduction)
Br- is a reducing agent, BrO3 is an oxidizing agent (synproportionation (comproportionation)).
Reactants:
Products: