Br2 (aq) + 2 KF (aq) → 2 KBr (aq) + F2 (g)
This is an oxidation-reduction (redox) reaction:
2 Br0 + 2 e- → 2 Br-I (reduction)
2 F-I - 2 e- → 2 F0 (oxidation)
Br2 is an oxidizing agent, KF is a reducing agent.
This is a gas evolution reaction, F2 is the formed gas.