The six protectors refer to the 6 troll mini-bosses in The Temple of Atal'Hakkar. Colectively they are required for both the Level 50 classes quests for Warriors, Shamans, Warlocks and Alliance Paladins as well as to lower the force field protecting Jammal'an the Prophet.
These trolls are ranged around a circular room on the fifth floor of the temple (the circular room is the 4th floor, the trolls are located the floor above that). Working clockwise from the Northeast platform, the trolls are named: Loro (NE), Hukku (East), Mob:Zul'Lor] (SE), Gasher (SW), Mijan (W), and Zolo (NW).
The trolls are mini-bosses and each has a different ability some of which can make the battle a bit tricky. These will be listed in brief here, please look at the mob page for more detail.