Ch 12.1 in Hebrew.

Jehoash: The new king is called “Joash” in verse 2 of this chapter, but here and in the following verses in chapter 12, the longer form of the same name is used. In order to avoid confusion, the shorter form should be used throughout the Bible when referring to the king of Judah with this name. The king of Israel bearing the same name would then be referred to consistently as “Jehoash,” using the longer form of the name (so Good News Translation). In this way readers will be better able to distinguish between the two rulers. See Appendix B, “Who’s Who among the Kings?”

Seven years old: It becomes clear at this point that Joash was only a year old when the events described in verses 1-3 took place. He became king about 835 B.C.

When he began to reign: It will be quite appropriate to add “over Judah” at the end of this clause. In certain languages the model of Good News Translation will be helpful for translating the verb here (“became king of”).

There is a difference in the chapter division here between most English versions on the one hand and Roman Catholic versions like New American Bible and New Jerusalem Bible on the other hand. This is because the modern Catholic versions follow the numbering system of the Hebrew text while the English tradition generally stays with the chapter division of the Latin Vulgate. Translators are advised to adopt whichever system is already commonly known by Bible readers in their area. This means that in countries where French or Spanish is spoken, the Hebrew system should be adopted and verse 21 should become the first verse in chapter 12. But in translations that will appear in countries where English is the national language, the Latin Vulgate system should probably be followed.

Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Kings, Volume 2. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here .