the priest is to examine the person. If the scaly outbreak has spread on the skin, the priest does not need to look for yellow hair; the person is unclean.
the priest is to examine the condition. If it appears to be deeper than the skin, and the hair in it is yellow and sparse, the priest must pronounce the person unclean. It is a scaly outbreak, a serious skin disease of the head or chin.
But if as far as he can see, the scaly outbreak remains unchanged and black hair has grown in it, then it has healed; he is clean. The priest is to pronounce the person clean.