Most coders avoid using global variables, because the code that depends on them can be difficult to test and maintain. They are also averse to naming conflicts with local variables. Globals are variables, available throughout the code, so they have no scope, whereas local variables scope is restricted to where it is declared.
The answer you expect to get here is that the candidate builds reusable code, using module pattern or class inheritance, because these approaches will let multiple developers work on one project easily. Plus, it’s easier to test classes or modular code.
“This” keyword points to the object currently in scope, which owns where you are in the code. For example, if you are in an object created with a new keyword, “this” will refer to the object that is being created.
This, of course, is an open-ended question that will help you see how the candidate feels about open source, whether they stay informed about the new technology options in their field, how they make choices on what frameworks to use, and so on.