You shall make the frames for the tabernacle seems to be an unnecessary repetition, but it introduces the details mentioned in verses 18-22. Revised Standard Version uses the colon to indicate this, but this is a punctuation mark that is not read aloud. New American Bible makes this understood: “Set up the boards of the Dwelling as follows:….” Good News Translation leaves implicit the information that the frames are for the Tabernacle.

Twenty frames for the south side indicates that the length of the tabernacle was to be twenty times the width of each frame (1.5 cubits), or thirty cubits in all (about forty-five feet, or 13.7 meters). Two words are used for south, literally “for the side of the Negeb toward the right.” The basic orientation was facing the east, so south was on the right, and the Negeb was the name for the desert area south of Palestine. (See the introductory comment above.)

And forty bases of silver you shall make uses another word whose meaning is not clear. Bases is translated as “pedestals” in New American Bible and Durham, and as “sockets” in New Jewish Publication Society’s Tanakh, Revised English Bible, and others. The context is clear, however, that these were to be the silver pieces or “stands” (Contemporary English Version) into which the tenons at the bottom of each frame were to be inserted. You shall make does not indicate how these bases were to be made, but 38.27 tells us they were made by “casting,” or by pouring melted silver into a mold. The fact that there were forty bases means that there was one base for each tenon, or two bases under one frame for its two tenons. The repeated phrase, and two bases under another frame … simply means, as Good News Translation expresses it, that there were to be “two bases under each frame.”

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 .