This verse is a concise summary of two key events:

"Hezekiah slept with his fathers..." This is a common idiom in the Old Testament to indicate that a king has died and been buried with his ancestors. It's a euphemism for death, suggesting he has joined his forefathers in the afterlife.

"...and Manasseh his son reigned in his place." This signifies the transfer of power. Hezekiah's reign has ended, and his son, Manasseh, has succeeded him as king.

In essence, the verse simply states that King Hezekiah died and was succeeded by his son, Manasseh, as king of Judah.

The importance of this verse lies in its placement within the biblical narrative. It marks the end of Hezekiah's reign, which was generally considered a righteous one, and the beginning of Manasseh's reign. Manasseh's reign is often characterized as one of the most wicked in Judah's history, so this transition is significant.