When a player or an item is thrown on a pressure plate, it gives off a redstone signal. The mod only adds wooden types. They do not generate naturally like how some minecraft pressure plates do.
Good for automated type doors, place in front of door and when player walks up to the door, they will trigger the pressure plate and open the door, all without having to click the door.
Also good or floor traps, or just traps in general. Since the mod adds colored ones, it is really good to use ebony planked hallway, and ebony secret trapdoors, as they are quite dark and hard to see with dark lighting.