וּשְׁנֵ֤י קְרָשִׁים֙ תַּעֲשֶׂ֔ה לִמְקֻצְעֹ֖ת הַמִּשְׁכָּ֑ן בַּיַּרְכָתָֽיִם׃
Farás duas tábuas para os cantos do Mishcan nos fundos.
Radak
וירכתו, as if the Torah had written ולירכתו as in Exodus 26,23 ולירכתו המשכן, “at the rear of the Tabernacle.”
Rashbam
ולירכתי המשכן תעשה ששה קרשים. Seeing that each board was one and a half cubits wide, this would cover nine cubits in width. This left one half cubit at the north west corner and at the south west corner unaccounted for, seeing the width of the Tabernacle was ten cubits. The area left exposed would be taken up by the boards arranged in the east-westerly (long) sides of the Tabernacle, the last half cubit of each filling these two voids. This left the inside dimensions of the Tabernacle ten cubits wide with the problematic corners being enclosed in the manner we described. The view from the outside of the Tabernacle would show 90 degree corners without any indentations whatsoever.
Sforno
אל הטבעת האחת, to the ring at the thickest point of the board forming the corner post. [we referred to this in verse 23 where these two boards are described as serving with one cubit in a westerly direction, completing the length of the structure and with the half cubit constituting its thickness closing the gap left on either side of the six boards forming the western wall of the Tabernacle. (compare Rash’bam there) Ed.] The bolts (bars) running alongside the walls were also inserted both in the lower level and the higher level (above the center bar) through the rings attached to these corner boards at the south-west and south-east of the Tabernacle respectively, ensuring that the structure was solid.