definition of oxidizing agent
Oxidation means increase in Oxidation state or loss in electrons.

Example: $\ce{Fe^2+ -&gt; Fe^3+ + e-}$

Oxidizing agent is a substance that oxidizes other substances and reduces itself.

In your example, $\ce{F2}$ will act as oxidizing agent as in the reactant side its oxidation state is $0$ but in the product side its oxidation state is $-1$, which means that its oxidation state in decreased, i.e. $\ce{F2}$ is reduced.