Albert Barnes Commentary 2 Kings 23:2

"And the king went up to the house of Jehovah, and all the men of Judah and all the inhabitants of Jerusalem with him, and the priests, and the prophets, and all the people, both small and great: and he read in their ears all the words of the book of the covenant which was found in the house of Jehovah." — 2 Kings 23:2 (ASV)

The prophets - The suggestion to regard this word as a scribal error for “Levites,” which occurs in Chronicles (see the marginal reference), is unnecessary. For though Zephaniah, Urijah, and Jeremiah are all that we can name as belonging to the prophetic order at the time, there is no reason to doubt that Judea contained others whom we cannot name. “Schools of the prophets” were as common in Judah as in Israel.

He read - This passage is strong evidence that the Jewish kings could read. The solemn reading of the Law—a practice commanded in the Law itself to be done once every seven years (Deuteronomy 31:10–13)—had been neglected for at least the last 75 years, since the accession of Manasseh.