Answer:
(see below)
Explanation:
A reflection across the y-axis is the same thing, but just mirrored on the other side. In this case, "the other side" is the y-axis.
The original rectangle was two units away from the y-axis, so this new rectangle needs to be as well.
Its area needs to also be 2 units big.
Pretty much, it's the same thing and you just place it up to a mirror.
Refer to the image below: