Every player will choose a role, and will then choose two schools from within that role: one as a primary and one as a secondary. Both schools have four abilities and an Ultimate ability, but the Ultimate is only available from the primary school. The secondary school abilities will also be a bit more restricted in their use.
Want to see some of this in action? Then check out the video just past the cut, showing off some of the abilities of the Baresark school from the Warrior role. If you like hitting things with a large weapon, it's your sort of school.
[Thanks to everyone that sent this in!]