Hilkiah (verse 13) was the High Priest during the period that Josiah ruled over Judah (2 Kgs 22.8-20). It was he who discovered the book of the Law and read it to the king.
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Chronicles, Volume 1. (UBS Helps for Translators). Miami: UBS, 2014. For this and other handbooks for translators see here .