In short - Free distribution of this program is encouraged. You are free to use it as you prefer, to modify it, to use parts of it in any other program you are working with or developing (as long as it is also GPL'd), and, in short, do as you please with it. If you modify it in any useful way, I ask you to share it with me and the community. If you choose to modify the program, the result must remain under this same license.
Should you redistribute this program, the copyright notice and the GPL license must also go together with it.
The program is NOT guaranteed to be useful. It is NOT guaranteed to work. It is NOT even guaranteed not to harm your system. Use it at your own risk.