Dev:BackBoardServices.framework

BackBoardServices is a framework that was introduced in iOS 6.0. It communicates with the backboardd daemon that now does a lot of stuff that SpringBoard used to do. One can launch apps, kill apps, set backlight level, etc with that framework.

Killing an application
Replace com.apple.mobilesafari with the application's bundle identifier.

The last two arguments are used for the description, where the first is an unknown integer (use 1), and the second is your reason. These two arguments are not compulsory, but are followed by good practice.

Killing all applications
Again, it is not mandatory to specify a description but it is a good thing to consider doing.

Setting Backlight Level
The factor should be a number from 0.0 to 1.0, inclusive.