Your example is wrong. You can't attach object properties to a function.

Javascript context is pretty simple. The keyword 'this' by default points at the object that the method belongs to. When you invoke this function :

myRide.drive();

the myride object owns the drive function, so any keyword 'this' inside of the drive function will be referring to the myride object.

when you do this:

letsDrive = myRide.drive;

letsdrive is now a function that belongs to the global object (window) since we did not declare an object for it. So 'this' is reffering to the window object.To get the output in your example, you would say

window.model = 'Mercedes';

And invoking letsdrive() will now return the expected result