en_tn/2ki/16/15.md

the large altar

This refers to the new altar that Ahaz told Uriah to build.

the king's burnt offering and his grain offering

When Ahaz said "the king" and "his," he was referring to himself. The king treated his offerings as special. Alternate translation: "my burnt offering and my grain offering" or "the royal burnt offering and royal grain offering" (See: rc://en/ta/man/translate/figs-123person)