Magic is inherent in the world, though most people can go for their whole life without witnessing it. The elves and, to some extent, the orcs are able to force their will onto the world, but humans must learn words of power. This paper will examine both forms.
Internal magic seems common among elves, with even small children able to cast minor spells. Elven magic ranges from simple presdigitation to the ability to summon elemental forces. A few orcs demonstrate these powers as well; they become the shamans and spiritual leaders of their tribes. This trait is passed by blood and the elves are always sure to breed mage bloodlines together. Over the millennia this has created a caste of powerful individuals that guide the elven race to their genetic pinnacle. Being passed by blood some members of the half-breed races have an inherent talent for the arcane.
External magic, the magic of humans, is a language developed by the Ministry of War in order to combat elven mages. Arcanists must train for years to be able to recall these words in the stressful conditions often found on the battlefield, but the Academy of Arcane at Maran has been supplying the Empire with an increasing amount of casters. The language works by invoking the true names of things and then describing them and forcing the creations into being. While this allows for the calling of weapons or armour, even fortresses, the magic cannot be used to change.
This is the second fundamental difference between the two magics. Elven magic alters and human magic creates. These can be used to the same end; elves will superheat the air and humans will produce fire, but both methods will result in a fireball. On the other hand, elves can heal wounds with a touch, a powerful ability inaccessible to the Empire. The Empire can fabricate large amounts of materiel for their armies, while elves must smith or shape every sword individually.
Magic is continually evolving, with new words being defined and refined daily. As an initiate you will likely enter your chosen field with a superior repertoire than current practitioners. However most choose to return to the Academy and expand their knowledge every few years. This is especially important for those serving with the Imperial Guard.
I hope you now have a greater grasp of what you will be learning in the next few years.