This is the law of the plague of leprosy in a garment of woollen or linen, either in the warp, or woof, or any thing of skins, to pronounce it clean, or to pronounce it unclean.
This verse says that when checking for the plague of leprosy in fabrics like wool or linen, whether it's in the weaving threads or the fabric itself, you must determine if it is clean or not.