What's an iphone 5 sync cable for?

They synchronize information across devices, but what does "synchronize information" mean? Could you give an example?

Transferring pictures/videos/music/other content from your iPhone to your computer or vice versa.

The sync cable is used to establish a data connection between your computer and iPhone. In other words, you can transfer videos, photos and music to and from your iPhone to a computer with iTunes (if not just transferring photos from My Computer).