Pivot tables are a powerful excel features that allows users to organize their data with the click of a button. Useful for quickly analyzing large sets of data, pivot tables allow you to quickly find the measures of central tendency, frequency of data entries, as well as sums, products, and more. To dig into an example, check out the pivot table below:

To highlight some useful functions, imagine a business that has a system of keeping track of client transactions. The table above contains information regarding the donorID, which is a unique identifier for each donor. If a business owner was interested in keeping track of their most frequent and largest donors, trending dates in which donations are more likely, or the average donation, all of this information would be available at the click of a button.

Source: https://www.perfectxl.com/excel-glossary/how-to-use-pivot-table-excel/