וַיָּבֵ֣א אֶת־הָאָרֹן֮ אֶל־הַמִּשְׁכָּן֒ וַיָּ֗שֶׂם אֵ֚ת פָּרֹ֣כֶת הַמָּסָ֔ךְ וַיָּ֕סֶךְ עַ֖ל אֲר֣וֹן הָעֵד֑וּת כַּאֲשֶׁ֛ר צִוָּ֥ה יְהוָ֖ה אֶת־מֹשֶֽׁה׃ (ס)
And he brought the ark into the tabernacle, and set up the veil of the screen, and screened the ark of the testimony; as the LORD commanded Moses.
Read Kabbalistic (mystical) interpretations of Exodus 40:21: Zohar and classical Jewish mystical sources, free online.