If description displays emotion, but they cant feel certain emotion, then what is a way one can write that without creating too boring of a piece and still display what they are going through?
description displays emotion
This is a sound piece of basic advice given to authors. It is correct, but by no means literal. For example "the trees blocked out the dark sky and the shadows merged to a single carpet of darkness" displays more emotion than "the forest was dark".
However, lack of description does not imply lack of emotion. The sky could still be gloomy, regardless of the emotions that the protagonist is, or is not experiencing.
Instead, forget this particular piece of advice and instead ask yourself how to relay lack of emotion. Find something that you are neutral about, like a new and improved version of your sister's shampoo. Find something that you have no opinion or emotion about whatsoever and think about how to write the story.
For example, "she looked at the gaudy January sale rack with a flat expression, she turned away without really acknowledging any of the offers" or "she watched his rant with just a slight raising of her perfectly plucked left eyebrow, she patiently waited until his fury began to wain". Plenty of description, flat emotion.
So think lack of interest/reaction, not lack of description.