تُرِيكَ إِذَا دَخَلَتْ عَلَى خَلَاءٍ وَقَدْ أَمِنَتْ عُيُونَ الْكَاشِحِينَا
When she enters a place of privacy and feels safe from the eyes of hostile observers, she reveals her appearance to you.
Khalāʾ denotes a private setting. Al-kāshiḥūn are ill-wishers or hostile observers. The verse establishes the condition of privacy and safety from their gaze before the poet begins his detailed comparisons.