When you run a Java program from the command line, you can add arguments to tell the JVM to act a particular way or to pass information to your application. (That's how the args parameter in your static void main(String args) method gets filled.) For example:
The -ea and -DDEBUG_LOW are VM arguments. The arg1, arg2, arg3 are program arguments.
So when you run the program from Eclipse, that screen allows you to enter your VM and application arguments.