Pilea plants are definitely light lovers and will struggle in low-light environments. But it is also important that you do not place your Pilea in direct sun as this will burn the leaves and can cause your plant to turn red and then brown.
You may begin to notice that your Pilea is reaching for the light and is growing lopsided. If this is the case, make sure to rotate your Pilea plant every few days to make sure it grows straight.