These are fences that when powered, they generate light. They are the standard fence highth of 1.5 blocks tall meaning mobs can't jump over them. These are ideal for farms for the light they give off stops mobs from spawning and if any venture close they cannot jump over it and trample your crops.
There are currently two different color Illumifence. Red, and Blue IllumiFence. The Red IllumiFence is crafted the same way as normal fences but replacing the sticks with red stone dust. As for the Blue IllumiFence, it is the same as with the Red but replace the red stone dust with Lapis Lazuli.