What does 2 Kings 21:1 mean?

2 Kings 21:1 KJV
Manasseh [was] twelve years old when he began to reign, and reigned fifty and five years in Jerusalem. And his mother’s name [was] Hephzibah.

2 Kings 21:1 MKJV
Manasseh [was] twelve years old when he began to reign. And he reigned fifty-five years in Jerusalem. And his mother’s name [was] Hephzibah.

2 Kings 21:1 NKJV
Manasseh [was] twelve years old when he became king, and he reigned fifty-five years in Jerusalem. His mother’s name [was] Hephzibah.

2 Kings 21:1 KJV 2000
Manasseh was twelve years old when he began to reign, and reigned fifty and five years in Jerusalem. And his mother’s name was Hephzibah.

Interlinear KJV

Manasseh /M@nashsheh/ was twelve /sh@nayim/ /`asar/ years /shaneh (in pl. only),/ old /ben/ when he began to reign, /malak/ and reigned /malak/ fifty /chamishshiym/ and five /chamesh/ years /shaneh (in pl. only),/ in Jerusalem. /Y@ruwshalaim/ And his mother’s /’em/ name /shem/ was Hephzibah. /Chephtsiy bahh/

Matthew Poole’s Commentary

Manasseh’s idolatry, 2Ki 21:1-9. Judgments prophesied against Judah, 2Ki 21:10-15. Manasseh shed innocent blood; dieth, 2Ki 21:16-18. Amon his son succeedeth him; and is slain by his servants; who are slain by the people: Josiah his son is made king, 2Ki 21:19-26.

Ver. 1. Reigned fifty and five years in Jerusalem; in which time the years of his imprisonment are comprehended, 2Ch 33:11.