Answer
This is a redox reaction. Ba acts as a reducing agent and $Cl_{2}$ acts as an oxidizing agent.
Work Step by Step
In a redox reaction, there is a change in oxidation number. The oxidation number of Ba changes from 0 to +2; there is an increase in oxidation number. Hence, it acts as a reducing agent.
$Cl_{2}$'s oxidation number changes from 0 to -2; there is a decrease in oxidation number. Hence, it acts as an oxidizing agent.
