The "this" keyword refers to the current instance of the class. In the example you provided, whether you use this or not, it have the same meaning.
Consider the following example
private int myVar;
public MyClass(int myVar)
In the above example, you have a constructor that uses the same variable name "myVar". so inside the constructor, simply refering "myVar" means the argument, and this.myVar refer to the class variable.
Hope this helps.