These verses contain the preliminaries of the ceremony of consecration. Aaron and his sons are to be brought to the door of the tabernacle, together with all that is necessary for the performance of the rite that is about to take place.
The words in the second verse, a bullock for the sin offering, and two rams, and a basket of unleavened bread, should be translated, the bullock for the sin offering and the two rants and the basket.
The garments, the anointing oil, the bullock, the two rams, and the basket of unleavened bread and cakes, had all been previously enjoined, when Moses was on the mount (Exodus 28:1-43, Exodus 29:1-46, Exodus 30:1-38).
These previous injunctions are referred to in the words, This is the thing which the Lord commanded to be done (Leviticus 8:5).