for example in the obedience parts. You can tell your decoy to just stand around and you tell your dog to heel. When he shows the correct behavior you click and release him to get the decoy.
Or you can also click your dog for barking when he apprehends the decoy.
I don't think anyone actually clicks his/her dog for biting guess that's pretty much self-rewarding
On this side you find two clips with Barking. I train my patroldog with a system like clicker. This both dogs trained for SAR. For Protection work I need the clicker for barking.