What is a lua unlocker?

[Serhawtt]

Title, keep seeing it said have no idea what it is

[Confucius]

Lua is a scripting language that comes from C. WoW API uses Lua for stuff like the interface, which allows developers to make addons for the game in Lua. A lua unlocker lets you use functions that Blizzard doesn't want players to be able to use, like functions to cast a spell and control movement, which allows for rotation macros and the such.