Aggregate fields are shown after all PDF Tables and before T&C content. These are primarily used to show Grand Total, Total Discount, Tax, Shipping and handling, VAT etc.
Please note that these field are different than Aggregate Fields in PDF Table. Aggregate Fields in PDF Table are pertaining to the aggregate value of a particular column within that table, while these fields are used to show aggregate value of entire PDF. Also, Aggregate Fields in PDF Table pull details from related list e.g., QuoteLineItem, while these Aggregate fields pull details from parent object which is selected in the Object field, e.g., Quote or Opportunity.
Field configurations are same as explained in PDF Columns and here is how aggregate values are shown below all the tables.
