Explanation

اللَّهُمَّ أَنْتَ السَّلَامُ وَمِنْكَ السَّلَامُ فَحَيِّنَا رَبَّنَا بِالسَّلَامِ. اللَّهُمَّ زِدْ هَذَا الْبَيْتَ تَعْظِيمًا وَتَشْرِيفًا وَمَهَابَةً وَتَكْرِيمًا، وَزِدْ مَنْ حَجَّهُ أَوِ اعْتَمَرَهُ تَشْرِيفًا وَتَعْظِيمًا وَبِرًّا.

Translation:
"O Allah, You are Peace, and from You is Peace. Grant us life, our Lord, in Peace. O Allah, increase this House (the Kaaba) in honor, reverence, awe, and dignity. And increase those who perform Hajj or Umrah in honor, reverence, and piety."