en_tn/num/08/18.md

I have given the Levites as a gift to Aaron and his sons

Yahweh appointing the Levites to help Aaron and his sons is spoken of as if they were a gift that Yahweh were giving to Aaron and his sons. (See: rc://en/ta/man/translate/figs-metaphor)

I have taken them ... I have given them

Here "them" refers to the Levites.

instead of all the firstborn

The missing words may be added to make the meaning clear. AT: "instead taking all of the firstborn" (See: rc://en/ta/man/translate/figs-ellipsis)

when they come near

Here "they" refers to the people of Israel.