Yes for the hash browns to cook properly you should let the frozen hash browns sit out for at least 30 minutes to thaw somewhat to allow the hash browns to cook properly.
Or you can remove the hash browns from the freezer and place the frozen hash browns into the refrigerator overnight and then by morning or the next day when you're ready to cook the hash browns they'll be thawed out enough to cook.
You could cook frozen hash browns but the last time I tried cooking hash browns that were frozen they didn't turn out too good.
So I always let the hash browns thaw out properly first and then cook them and they turn out much better.
I just sit the hash browns in the refrigerator overnight to allow them to thaw out before cooking.