Answer
$Li$ is oxidized and $F$ is reduced.
Work Step by Step
1. Rewrite the equation to show the ions and the atoms:
$2Li(s) + F_2(g) --\gt 2Li^+(s) + 2F^-(s)$
2. Analyze what happens to each atom/ion during the reaction.
During this process, These are the charge increases/decreases:
$Li^0 --\gt Li^+$: The increase in charge indicates that $Li$ is oxidized.
$F^0 --\gt F^-$: The decrease in charge indicates that $F$ is reduced.