Console is a function of World of Warcraft game engine that allows access to an in-game console.
The console is turned off by default for players; however, it can be activated by adding "-console" to World of Warcraft command line. Once the console feature is activated, the player can access it by pressing the "~" key while in game. The console allows players to change game client settings by hand, such as those related to graphics and sound. However, most of those functions are already available via the game menus.
In addition, the console also allows access to a Game Master commands as demonstrated in videos from E3 and Blizzcon. However, those functions would report permission denied when evoked by players.