That's the number of injuries that afflicted NFL players over the 2011 season. This is kind of a scary statistic when you consider the NFL only has 1,696 active players at any given point. This is mostly minor injuries that only hold a player out of practice for around a week, but even those injuries can lead to missed games.
There is no greater shame in sports than when an athlete can't compete because of injury. It's like if you had the job of your dreams and you couldn't go because of something out of your control. It hurts the athlete most of all, of course. But other people are affected by it as well.