Since I was intent on summarizing and understanding the data from the Excel sheet, I focused on the Formulas page of the platform where your data can be input, then generated or explained.

you can still use the Sum function, but you'll need to reference the appropriate cells. This is simplified if the data resides in the same cell numbers on each sheet, because you can summarize ...

Pivot tables in Google Sheets summarize smaller sets of data from a more extensive table ... the most out of the pivot table you've created using other facets of the feature in Google Sheets.