Yahweh does the purifying. These three terms mean basically the same thing. AT: "Yahweh will purify, cleanse, and refine many people" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-doublet]])
The king of the north is the one who stops the temple sacrifices. AT: "the king of the North takes away the regular burnt offering and sets up the abomination that causes complete desolation" (See: [[rc://en/ta/man/translate/figs-explicit]])
This refers to an idol that will make the temple desolate, that is, that will cause God to leave his temple. See how you translated this in [Daniel 11:31](../11/31.md). AT: "the disgusting idol that will cause God to abandon the temple" or "the disgusting thing that will make the temple unclean" (See: [[rc://en/ta/man/translate/figs-idiom]])
"one thousand two and hundred ninety days" or "twelve hundred and ninety days." Here "days" refers to a period of time. Most commonly rendered as days, but can also imply years. (See: [[rc://en/ta/man/translate/translate-numbers]])