They cover both combat and gathering/crafting roles. Characters can mix up classes via their gear, as FFXIV has no actual level system.
The Armoury system is what decides a characters array of abilities. There are 4 groups of classes that Square developed; Disciples of War are the Pugilist, Gladiator, Marauder, Archer and Lancer. Disciples of Magic are Conjurer and Thaumaturge.
The two remaining groups are Disciples of the Land, which are gatherer classes Miner, Botanist and Fisher. Disciples of the Hand are crafters and they are: Carpenter, Blacksmith, Armourer, Goldsmith, Leatherworker, Weaver, Alchemist and Culinarian.
Square Enix plan for more classes to be added as time goes on. Final Fantasy XIV releases on PC this September, while the PS3 version currently has no release date.