جَعَلَ اللَّهُ الْكَعْبَةَ الْبَيْتَ الْحَرَامَ قِيَامًا لِلنَّاسِ
Allah made the Ka‘bah, the Sacred House, a means of support for people.
Atf al-bayan adds clarification to a previously mentioned noun. “The Sacred House” illuminates the reference “the Ka‘bah” while also invoking its sacred status.
Apposition may simply clarify, or combine explanation with praise and esteem. One must derive the secondary force from the content and the larger context.