It's a new way of showcasing a persons profile through information shown on your profile. It focuses on friendships, photos and other personal information you made public on Facebook. Check it out on Google Images if you don't know what its looks like.
Don't worry you're not alone, many people including myself are confused about it. It flys in the face of the old saying if it aint broke, don't fix it. Basically you post your info & pictures on this time line of your life. It is ridiculous, you write something & bang, it ends up on a time line from 10 years ago. The worst part is that they came up with this idea, & implemented it. No hey this what we're going to do, would you like to try it out? No, just 1 day I logged in & looked at this mess. It may not be the dumbest thing ever invented but it was a great way to get people to bag facebook