rece = cold I have not encountered "frig" before, but my answer should also be accepted.
"rece" is an adjective while "frig" is a noun. Both translate as "cold" in English and even if Romanian native speakers often mix them, they should be used appropriately.
Camera este rece (the room is cold)
În cameră este frig (it is cold in the room)
It isn't cold here might be a more idiomatic translation