Source: Player's Handbook
You can turn or rebuke creatures more often than normal.
Prerequisite: Ability to turn or rebuke creatures.
Benefit: Each time you take this feat, you can use your ability to turn or rebuke creatures four more times per day than normal.
If you have the ability to turn or rebuke more than one creature (such as a good-aligned cleric with access to the Fire domain, who can turn undead and water creatures and can rebuke fire creatures), each of your turning or rebuking abilities gains four additional uses per day.
Special: You can gain Extra Turning multiple times. Its effects stack. Each time you take the feat, you can use each of your turning or rebuking abilities four additional times per day.
Normal: Without this feat, a character can typically turn or rebuke undead (or other creatures) a number of times per equal to 3 + his or her Charisma modifier.