en_tn/2ch/31/03.md

assigned the king's portion for the burnt offerings from his own possessions

Hezekiah took the meat and grain used for the burnt offerings out of his own possessions.

the new moons

This was a festival coinciding with the movement of the moon.

the fixed festivals

This refers to festivals which occur on specific dates.

as it was written in the law of Yahweh

This can be stated in active form. Alternate translation: "just as Moses wrote in the law of Yahweh" or "just as Yahweh commanded in his law" (See: rc://en/ta/man/translate/figs-activepassive)