Shall be: not at some distant future time, but “from now on.”

An everlasting statute: although the noun is singular in form, it clearly refers to the entire set of rules. In some languages it will be much more natural to translate it as a plural. The qualifying word everlasting is intended to indicate permanence. Together they may be translated “permanent regulations” or “rules that will last forever.”

That atonement may be made: this passive construction may be rendered actively with “the priests” as the subject.

Because of all their sins: or “to cleanse them from all their sins.”

And: in Good News Translation this is translated “So” and is set apart as a separate paragraph which is intended to highlight the summary nature of this statement.

Moses: as the Good News Translation footnote indicates, “Aaron” may be intended as the subject here. The text literally says “and he did just as the LORD had commanded Moses.” The pronoun “he” may be understood to refer to Aaron rather than Moses (as in Bible en français courant). New Jerusalem Bible avoids the problem by using the passive form: “And as Yahweh ordered Moses, so it was done” (similarly New International Version, An American Translation, and New American Bible). If the passive is not possible in the receptor language, translators may wish to make Aaron the subject in spite of the Revised Standard Version base and the Good News Translation model.

Quoted with permission from Péter-Contesse, René and Ellington, John. A Handbook on Leviticus. (UBS Helps for Translators). New York: UBS, 1990. For this and other handbooks for translators see here .