XSA is a Shell Archive, a container containing below information:
One or more .hwh files
AMD Vivado™ tool version, part, and board tag information
IP - instance, name, VLNV, and parameters
Memory Map information of the processors
Internal Connectivity information (including interrupts, clocks, etc.) and external ports information
BMM/MMI and BIT files
User and HLS driver files
Device tree files
Other meta-data files
Please refer to UG1725 for more details.