en_tn/2ki/15/22.md

Menahem lay down with his ancestors

This is a polite way of saying that he died. See how you translated this in 2 Kings 10:35. Alternate translation: "Menahem died as his ancestors had" or "like his ancestors, Menahem died" (See: rc://en/ta/man/jit/figs-metaphor and rc://en/ta/man/jit/figs-euphemism)

Pekahiah

This a man's name. (See: rc://en/ta/man/jit/translate-names)

became king in his place

The phrase "in his place" is a metaphor meaning "instead of him." Alternate translation: "became king instead of Menahem" (See: rc://en/ta/man/jit/figs-metaphor)