You can use formulas to log data within these cells and when your spreadsheet is small, it's simple enough to read through and understand the numbers.
But as your spreadsheet begins to grow, drawing conclusions requires a bit more power. That's where pivot tables come in. A pivot table takes a large set of data and summarizes it.

ex
--
Father food	2021/10/09
Mother shopping	2021/10/07
You	drink	2021/11/01
Mother food	2021/10/25
You	3c	2021/10/11
Father drink	2021/11/03

how can easily tell what you 3 buy?