Rust

I am pretty new to Rust and I find the docs can be a little confusing sometimes so I'd be really thankful for people who can help me understand this.

So for my uni project we are doing part of it in Rust. and I am having issues understanding how the modules function. So here is my example program.

Main.rs does some stuff and then passes a pointer into a function from a separate Rust file. That function then does some more things and passes a new variable into a function form another separate Rust file as a pointer.

main.rs has mod separate_file1; and then in separate_file 1 there is a mod separate_file2;.

The confusion is that separate_file2 does not read from the same directory as main.rs despite being in it. Instead it looks in a sub-folder under the same name.

If someone could explain to me why it works like this and what the best practice is for using modules I would be really thankful. It's made me struggle a lot.