Arcane magic is used by bards, wizards and sorcerers. For the most part, the distinction between arcane and divine magic lies in the story of how the magic is invoked — divine magic is granted by powerful beings residing in the outer planes of existence, while arcane magic derives from tapping into a "weave" of magic permeating reality. (Wizards study the nature of this weave, while bards and sorcerers are naturally attuned to it.) In terms of gameplay, the main difference between the two is that arcane spells with somatic components are subject to arcane spell failure from armor and shields. There are also some differences in how spells become available (although this could be viewed as more a difference between classes than between types of magic), but otherwise the game treats arcane and divine magic identically.
There are two ways arcane casters acquire access to spells (hence the reason this may be more a difference in classes than a difference in types of magic). Bards and sorcerers choose their spells at level-up (and at character creation, if starting as a bard or sorcerer). This gives them a highly limited spell selection, but they otherwise do not have to plan their spells in advance; they cast spontaneously. Wizards, on the other hand, need to plan their spells each day. Before resting, they need to assign spells to spell slots, which determines which spells can be cast the next day, as well as how often each spell can be cast. The spells they can choose from when filling spell slots gradually grows, with a few spells learned each wizard level and additional spells potentially learned from scrolls. If enough spells are learned from scrolls, a wizard could potentially know every wizard spell in the game, at which point their access to spells becomes comparable to divine casters.