en_tn/2ki/08/19.md

destroy Judah

Here "Judah" is a metonym for the people who live there. Alternate translation: "destroy the people of Judah" (See: rc://en/ta/man/translate/figs-metonymy)

since he had told him that he would always give him descendants

"since Yahweh had told David that he would always give David descendants." This refers to Yahweh's promise to David that his descendants would always rule Judah. The full meaning of this statement can be made explicit. Alternate translation: "since he had told David that his descendants would always rule Judah" (See: rc://en/ta/man/translate/figs-explicit)