When to use classes (OOP)?

I study/program on Python for a year, but I still can’t understand when to use the classes. Reading books and watching video lessons, I am aware of things such as encapsulation or, what is abstraction . But, when it comes to moments when exactly use OOP, I get into a stupor.

in my thinking, classes can be replaced with modules with a set of thematic functions. No Self 'ov before the variables and as the first argument of the methods, no class announcements before use, import and use.