The sides of the tabernacle westward - Rather, the back of the tabernacle toward the west. See Exodus 26:18.

And for the sides of the tabernacle,.... Or the ends of it, the east and west, and the account begins with the west:
westward thou shalt make six boards; so that the breadth of the tabernacle was but nine cubits, or four yards and a half, according to a common cubit; but two boards more placed at the two corners of the sides, next observed, added to the breadth of it.

Six boards were to be made for the back of the dwelling westwards (ימּה), and two boards "for the corners or angels of the dwelling at the two outermost (hinder) sides." למקצּעת (for cornered), from מקצּע, equivalent to מקצוע an angle (Exodus 26:24; Ezekiel 46:21-22), from קצע to cut off, lit., a section, something cut off, hence an angle, or corner-piece. These corner boards (Exodus 26:24) were to be "doubled (תּאמם) from below, and whole (תּמּים, integri, forming a whole) at its head (or towards its head, cf. אל Exodus 36:29) with regard to the one ring, so shall it be to both of them (so shall they both be made); to the two corners shall they be" (i.e., designed for the two hinder corners). The meaning of these words, which are very obscure in some points, can only be the following: the two corner beams at the tack were to consist of two pieces joined together at a right angle, so as to form as double boards one single whole from the bottom to the top. The expressions "from below" and "up to its head" are divided between the two predicates "doubled" (תּאמים) and "whole" (תּמּים), but they belong to both of them. Each of the corner beams was to be double from the bottom to the top, and still to form one whole. There is more difficulty in the words האחת אל־הטּבּעת in Exodus 26:24. It is impossible to attach any intelligible meaning to the rendering "to the first ring," so that even Knobel, who proposed it, has left it unexplained. There is hardly any other way of explaining it, than to take the word אל in the sense of "having regard to a thing," and to understand the words as meaning, that the corner beams were to form one whole, from the face that each received only one ring, probably at the corner, and not two, viz., one on each side. This one ring was placed half-way up the upright beam in the corner or angle, in such a manner that the central bolt, which stretched along the entire length of the walls (Exodus 26:28), might fasten into it from both the side and back.