Food which has been stored in a freezer without being properly wrapped or packaged can become dry and discoloured due to exposure to the air. This is known as freezer burn.
Freezer-burned food is still edible, assuming it’s not too ancient or hasn’t suffered some other deterioration. However, the flavour, texture, and nutrients will be lost or lacking. Therefore, it’s best to wrap or pack food carefully prior to freezing it so you can later benefit from the food at its best. When wrapping the food, take care to remove as much air as possible from the package and then seal the bag or wrapping.
Food kept in a freezer should be rotated so nothing gets lost in the back. Following the stock system of first-in-first-out (FIFO) is a good habit to get into.