They: the pronoun here refers to the priests. It may be wise to make this information more obvious in the receptor-language translation, as does Good News Translation.

Make tonsures upon their heads: this has nothing to do with natural baldness (as in chapter 13) but involves the intentional shaving of a part of the head to make a bald spot. This was done by some to mourn the dead. It is probably in error to say simply “shave their heads” as in New International Version, since this may give the impression that the entire head is necessarily shaved. The expression indicates rather the shaving of a part of the head to make one part of it bald.

Shave off the edges of their beards: see 19.27.

Cuttings in their flesh: see 15.7 and 19.28.

As in 19.27-28, these acts were performed as a sign of mourning for the dead. Good News Translation makes this implicit information explicit in translation by adding “to show that he is in mourning.” This should probably be done in most other languages, since the purpose of these actions would otherwise be impossible for the reader to know.

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 .