These are facebook friends that have an AoC account.
Pressing this icon that appears in the top left of your screen will make another screen appear. In this screen you are able to select gifts that you send to your allies. Inturn, if they are the right high enough level, they can send the gift back. They can however except any gift at any level. You can also use your facebook groups for a quick selection of people you want to send gifts to (i.e your Guild)
Titans are big units that are classified as Lengandry and therefore dont use any equipment. There are 7 Titans in total and you need your Allies to "Crank" them to work.
How to add AlliesEdit
On your home page to the bottom right there is a section with the title "My Top 200 Allies (Your Rank: )" and under that there is this:
Which will bring up your facebook friends list for you to select your friends. They even have a tab which is a list of your friends that play AoC.
To unlock more building lots you can either buy them with Blue Crystals (not recommended) or have a certain amount of Allies. To unlock all building lots you need 200 Allies.
Join a mass add that can be found in the forums.