As soon as the burqa was lifted, she glowed like the moon, but the stain/mark comes from her unveiled beauty.

This beautiful couplet describes the overwhelming impact of seeing true beauty. The poet says that the moment the veil was lifted, she shone like the moon. But the true depth of the feeling is in the second line: 'I am stained by her unveiled state.' It suggests that the beauty was so profound, so unforgettable, that it left a permanent, indelible mark—a 'stain'—on the lover's soul.