Answer
$\frac{3}{26}$
Work Step by Step
We know that $probability=\frac{\text{number of favourable outcomes}}{\text{number of all outcomes}}$
The total number of cards (the number of all outcomes) is $52$
There are $12$ face cards ($3$ in each of the $4$ suits), out of which half of them, $6$ are red. Thus there are $6$ "good outcomes".
Hence the probability here is: $\frac{6}{52}=\frac{3}{26}$