KJV:

11 And the way before them was like the appearance of the chambers which were toward the north, as long as they, and as broad as they: and all their goings out were both according to their fashions, and according to their doors.
12 And according to the doors of the chambers that were toward the south was a door in the head of the way, even the way directly before the wall toward the east, as one entereth into them.

NASB:

11 The way in front of them was like the appearance of the chambers which were on the north, according to their length so was their width, and all their exits were both according to their arrangements and openings.
12 Corresponding to the openings of the chambers which were toward the south was an opening at the head of the way, the way in front of the wall toward the east, as one enters them.

‫יא  וְדֶרֶךְ, לִפְנֵיהֶם, כְּמַרְאֵה הַלְּשָׁכוֹת אֲשֶׁר דֶּרֶךְ הַצָּפוֹן, כְּאָרְכָּן כֵּן רָחְבָּן; וְכֹל, מוֹצָאֵיהֶן, וּכְמִשְׁפְּטֵיהֶן, וּכְפִתְחֵיהֶן.

‫יב  וּכְפִתְחֵי הַלְּשָׁכוֹת, אֲשֶׁר דֶּרֶךְ הַדָּרוֹם, פֶּתַח, בְּרֹאשׁ דָּרֶךְ; דֶּרֶךְ, בִּפְנֵי הַגְּדֶרֶת הֲגִינָה, דֶּרֶךְ הַקָּדִים, בְּבוֹאָן.

The door that is written about here was already mentioned in the prophecy: Ezekiel 40:38. Through this door, the share of the meat from the peaceful sacrifices, which is supposed to be given to the Kohanim, is taken out of the gate and carried to the last building, located near a space of 20 cubits.