I've heard a lot of this patch/program, but what is it exactly?

Hi man.
Fed2001 has not been relesed yet. But with it you can edit all teams\leagues in the game. And it's easy too! You can edit the kits,boots, and balls!
If you want you can change the league or teams names, also player names. You can edit the players atributtes and even their height and weight. This program is great for making leagues!!

Cao!