A cubit shall be its length … its breadth means that it was to be about “18 inches long and 18 inches wide” (Good News Translation). That is about “45 centimeters” square. (Cubit is explained at 25.10.) It shall be square uses the same word as 28.16. Good News Translation places this first and then gives the dimensions. One may also simply say “It shall be eighteen inches square.” And two cubits shall be its height is literally “and double-cubit its height.” The word for height comes from the word for “stand up.”

Its horns refers to the horn-like “projections at the four corners” (Good News Translation). (Horns are discussed at 27.2.) Shall be of one piece with it means that they were to be carved from the same piece of wood as the sides (or top) of the altar. As in the case of the altar of burnt offering, they were not to be made separately and then attached to it. This was also a requirement for the cherubim on top of the pure gold cover for the Covenant Box (25.19). Contemporary English Version has “make each of its four corners stick up like the horn of a bull.” This is a helpful model, but the reference to the horns being of one piece with it is not made explicit. So one may say “The four corners at the top should be carved from the same piece of wood and should stick up like the horns of a bull.”

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .