en_tn/num/08/16.md

each male child who opens the womb, the firstborn

These two phrases mean basically the same thing and are combined for emphasis. (See: rc://en/ta/man/translate/figs-parallelism)

male child who who opens the womb

This refers to the first male child to which a mother gives birth. (See: rc://en/ta/man/translate/figs-idiom)

I took the lives

AT: "I killed" (See: rc://en/ta/man/translate/figs-euphemism)

I set them apart

Here the word "them" refers to "the firstborn from among the people of Israel."