<u>Answer:</u> It helps in the oxidation of other substance and itself gets reduced.
<u>Explanation:</u>
Oxidizing agent is defined as the agent which helps in the oxidation of other substance and itself gets reduced. It undergoes reduction reaction in any redox reaction.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
Reducing agent is defined as the agent which helps in the reduction of other substance and itself gets oxidized. It undergoes oxidation reaction in any redox reaction.
Oxidation reaction is defined as the reaction in which a substance looses electrons. The oxidation state of the substance is increased.
<u>For Example:</u> Reaction of silver nitrate with copper metal, the equation follows:

The half reactions for the above reaction are:
Oxidation half reaction: 
Reduction half reaction: 
From the above reactions, silver is gaining electrons and thus is getting reduced and is considered as an oxidizing agent.
Copper is loosing its electrons. Thus, it is getting oxidized and is considered as a reducing agent.
Hence, it helps in the oxidation of other substance and itself gets reduced.