Like the name suggests just give some fluff for your army. You could tie in some epic battles in which you snatched victory out of the jaws of defeat. Or talk about how that one squad turned the tide of battle with that one act. The purpose is to mainly give inspiration to those who want to make a story for their army but don't have a lot of ideas (like me).
Don't forget to have fun with it. (yes i used a smiley)