And you shall couple five curtains by themselves is literally “And you [singular] shall join five tent-fabrics alone.” This means, as Good News Translation renders it, “Sew five of them together in one set.” And six curtains by themselves means to sew “the other six in another set” (Good News Translation). As explained at verse 3, these pieces were to be sewn together along the sides, not at the ends. Again five widths of four cubits each become twenty cubits, so the size of the first set will be twenty cubits by thirty cubits, or about ten by fifteen yards. And six widths of four cubits each become twenty-four cubits, so the size of the second set is twenty-four cubits by thirty cubits, or about twelve by fifteen yards. Contemporary English Version has a helpful model: “Sew five of the sections together to make one panel. Then sew the other six together to make a second panel.”

And the sixth curtain, or piece of cloth, refers to the additional piece of material in the second set. You shall double over means to “fold” it back over itself, so that it covers only two cubits of space. At the front of the tent means that this folded portion is to be placed at the entrance into the tabernacle when it is finally set up. Good News Translation has “Fold the sixth piece double over the front of the Tent”; Contemporary English Version has “and fold the sixth section double over the front of the tent.”

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 .