The “Supernatural” or the “Paranormal” is that which is not subject to the laws of nature - it exists above and beyond nature itself. As Witches and Wizards, we ourselves are Supernatural as such - as we possess powers which allow us to defy the laws of nature. Only those of Magical Blood can see and interact with the Supernatural. This includes Squibs and other humanoid-witches or wizards, such as Hags and Veela.
This being said, Muggle Attitudes are quite prominent towards the Supernatural, as the concept of the Supernatural is often closely linked to Philosophy and Theology. Many a Religion depicts Supernatural Entities such as Spirits, Angels, Demons and Djinns. Many who do not believe in the Supernatural often look to Myth to explain Supernatural Creatures, such as the Wendigo from Inuit Mythology or Vampires from Transylvanian and Scandinavian Myth.
There is a lot of Magic involved with the Supernatural: however most of the Magic is extremely Archaic, so the practices are different to normal Magic. It is not as simple as waving wand and reciting a spell - the Spells are usually longer, and require a more precise technique to it. Other Magical practices include Summoning and Banishing Spirits, communicating with them through Ouija Boards or Exorcising Demons.
As part of your Course in the Supernatural, you will also be learning how to kill, banish or expel an entity, as a method of self-defence. This includes learning the different substances and metals which can harm an Entity, and the method of which each can be killed.