The App scans through the list of email addresses in your phone’s contacts and then presents you with a list of people on Facebook with that email address. The list shows the persons name, profile picture, and an Add button to send them a friend request. For me at least it also presented some people who are not in my contacts, so there may be some glitches in the system, or some false positives on the email address match.
The Android version also allows you to tag people in status updates using the @ symbol in the same way as the desktop browser version, but this has not yet been added to the iPhone version.
On the Android version, the Find Friends option is clearly labelled at the top of the screen, but on the iPhone version it is hidden, and you need to go to the Friends tab, then click the Share button top right to find the command.
Lover of all things relating to Social Media, writer for TechontheGo.co.uk, and keen poker player.