Aaron shall make atonement is literally “And Aaron shall cover” or “make amends.” The Hebrew word kipper means “to cover,” but it is frequently used in the sense of covering over sins. (See the comment on atonement at 29.33.) New Revised Standard Version improves on Revised Standard Version, “Aaron shall perform the rite of atonement,” but Good News Translation is better: “Aaron is to perform the ritual for purifying the altar.” All this is implied by the reference to its horns. (See verse 2.) Once a year is literally “once in the year.”

With the blood of the sin offering of atonement is literally “from blood of the sin [offering] of the coverings-over.” The sin offering refers to “the animal sacrificed for sin” (Good News Translation). (See the comment at 29.14.) The act of “covering over” refers to the ritual of “purifying” (Good News Translation), which in this case is “purifying the altar.” This evidently involved taking blood from the larger altar outside and smearing it on the four projections of the smaller incense altar that was inside the Holy Place. Once in the year is repeated for emphasis. An alternative translation model for the first part of this verse is “Once a year Aaron must purify the altar. He will do this by taking blood from an animal that they have sacrificed for sin, and smearing it on the four horns of the altar” or “Once a year Aaron must take the blood of an animal that has been sacrificed for sin, and smear it on the four horns [or, projections] of the altar. In this way he will purify the altar.”

He shall make atonement for it is literally “he shall cover over [or, appease] upon it.” This repeats the first part of the verse, but the phrase “upon it” refers to the “altar” rather than the horns. So for it is the better translation. Throughout your generations is identical to verse 8. It is most holy to the LORD is literally “holy of holies this [is] to Yahweh.” Good News Translation handles it well, “completely holy, dedicated to me, the LORD.” New Jerusalem Bible has “It is especially holy for Yahweh.” Contemporary English Version has “The altar is sacred because it is dedicated to me.” The it refers to “the altar,” so New American Bible makes it explicit: “This altar is most sacred to the LORD.”

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .