1.) The "instanceVariable" in your screenshot is NOT an instance variable. It's called a local variable because you declared it inside a method. So the name is misleading. Local variables are visible by default in the variables view.
2.) Real instance variables would be visible in the debugger by default when you would open the "this" field in the debug view. But because you are only using the static main() method there is no instance of a class involved and therefore there is no "this" and no instance variables. You will need something more "complex" in order to see more information in the variables view