Hope this helps:

https://community.pega.com/knowledgebase/articles/configuring-application-bulk-upload-data-using-excel-spreadsheet

Hi,
To use Excel for uploading data in bulk, you must create the following items:

An Excel template
A binary file to save the Excel template
Download and upload activities
A user interface section that uses controls for downloading and uploading the template

OOTB activity:@baseclass.MSOParseExcelFile is useful for your requirement. It has a Java step where the whole logic is written in it.

Thanks,
Abhinav