Freezer burn is simply the result of air coming into contact with food, and while the color changes and dry spots it creates may not look appetizing, freezer burned food is, in fact, completely safe to eat.
If the damaged area is small, cut it off before or after cooking to preserve the quality of your meal. If the damage is extensive, consider tossing the food. While safe to eat, the quality will be poor.
To prevent freezer burn in the future, refer to these resources: