They refer to the silver shovel which he will using especially for the purpose of removing the ashes. The actual intention of these words is that the priest should remember that he must not begin his task until he has washed at the copper laver. In spite of the fact that he is already pure, and has even purified himself through immersion, one is still forbidden to begin any sacred Temple service (or even to draw near to the altar) until he "sanctified" his hands and feet at the laver. Thus the verses state (Ex. 30:20-21): "From there, Aaron and his sons shall wash their hands and feet; when they go into the Tent of Meeting, they shall wash with water so that they do not die; or when they come near to the altar to serve, to burn an offering made by fire to the L-rd, so they shall wash their hands and their feet, so that they will not die. And it shall be a statute for ever to them, to him and to his seed throughout their generations."
Even though the priest is certainly diligent and G-d-fearing, and well aware of the necessity for this sanctification without being told, it is still incumbent upon his brothers to warn him... for he goes to the altar alone, and as he is only human, he may forget this aspect of his duty. Once they have cautioned him, he stands forewarned.
At this time the other priests also remind him that the special shovel he will use for the ashes (one of the 93 vessels whose position was checked during the dawn patrol) is kept in the corner between the western side of ramp and the southern side of the altar. It will be there waiting for him.