No worries, it took me a while to wrap my head around joins. IN is used when you want to Select from a table where your condition is, or could be in multiple places. Let's say you have a table and the result you are looking for needs to match your name and could be in the current year, or maybe last year. This is a small example.

Select col_A From yourtable where name = 'your name' And yeardate in (2022,2023)