וְנָתַתָּ֤ה אֹתוֹ֙ לִפְנֵ֣י הַפָּרֹ֔כֶת אֲשֶׁ֖ר עַל־אֲרֹ֣ן הָעֵדֻ֑ת לִפְנֵ֣י הַכַּפֹּ֗רֶת אֲשֶׁר֙ עַל־הָ֣עֵדֻ֔ת אֲשֶׁ֛ר אִוָּעֵ֥ד לְךָ֖ שָֽׁמָּה׃
И положи его перед завесой, которая находится под ковчегом откровения, перед покровом ковчега над свидетельством, где я встречу тебя.
Rashi
לפני הכפרת BEFORE THE PARTITION VEIL — But this vail was drawn across the entire width of the Tabernacle, and you may perhaps say that the altar was not to be placed exactly before (exactly in a straight line with) the Ark but might be withdrawn from the straight line to the North or to the south since in that position, too, it would be before the partition vail; therefore it states further, “before the covering of the Ark”, i. e. exactly in front of the Ark but outside the veil.
Chizkuni
לפני הפרכת, “in front of the curtain that covers the Ark.” In other words, in the middle of the Sanctuary.