How the method of the class beings passed aound?

With respect to previous commenters, I think it's important to understand (as Ms. Boucher says) that class is just syntactic sugar for prototypes.

Any object can access a property/method on one of its prototypes. Consider the following:

const greeting = "Hello";
greeting.toLowerCase(); // "hello"

It looks like the method toLowerCase is being accessed on greeting itself, but greeting is just a string... In fact, it is a method of the prototype of the global String object (hence MDN's docs reference to 'String.prototype.toLowerCase'), but greeting can access it because a string automatically shares the same prototype as the String object.

This is all that class does in JS: when you 'instantiate' a class, you create an object and tell it to share the same prototype as the 'class' object, which contains the methods. Therefore you can call them on the 'instantiations' through prototypical inheritance. It is not 'passed around', it is 'borrowed' or 'accessed' from a prototype.

I hope this helps!