I'm kind of confused how SCSS works in Jekyll after reading the docs

In the step by step it says to have one SCSS file in /_sass/ with the actual code as well as another SCSS file in /assets/css/ that just includes the other…so like I just don’t understand the purpose of having two files, or the _sass directory in general if jekyll can just compile scss from anywhere

The ones in the sass folder could be referred to as partials - you could make separate files for different things like tables or nav or whatever you want, that allows you to have small files where everything related to that thing is located and can make it easier to manage than having one huge file. I probably have 10 or so partials in the sass folder.

Then all those get imported into the one scss file. The is the file you will load in the head of each page as actual css (in the source it needs to end in .scss but jekyll will compile it and output it as .css).

As I understand it jekyll needs to know where the actual sass files are in order to process them as sass - thus the default is the _sass folder but you can change it in the config file if you want.

You don’t have to use sass though, you can just use one css file if you like that.