10 BiBr3 + 6 KMnO4 + 24 H2SO4 → 5 Bi2(SO4)3 + 6 MnSO4 + 3 K2SO4 + 24 H2O + 15 Br2
This is an oxidation-reduction (redox) reaction:
30 Br-I - 30 e- → 30 Br0 (oxidation)
6 MnVII + 30 e- → 6 MnII (reduction)
BiBr3 is a reducing agent, KMnO4 is an oxidizing agent.