The Imam is a unique Ottoman unit that heals other units in Age of Empires III. This unit replaces the Monk (Age of Empires II)/ Priest (Age of Empires III) but the stats remain the same. Just like any other healing unit, the Imam has a poor attack, but can heal other units at a short range.
Only the Ottomans can send Imams from their Home City or train them from the Mosque after reaching the Colonial Age. The Imam can only be trained at the mosque which is another building only available to the Ottomans. Units do not regenerate their health on their own, so Imams can prolong the life of your armies significantly