The campfire is a Workspace which can not be moved once placed. It is made by placing a Flat Rock on the ground (the camp fire will appear on the beveled side of the rock), adding 2 Hammer Rocks and 3 Chopped Wood and craft (default hit 'G' button).
It will burn out over time but can be re-stoked by having another chopped wood in your hand and right click the fire. Camp fires are used to fry meat for example and provide for a very brief time a light source at night. They are used to harden gathered fresh wood too (place them next to the fire on the ground, hit the crafting button, the fire must burn for this to work).