For the most part you got your normal role's Attacker/Buffer and Defender. Once you pick up weapon's you will also have skill's on the Dashboard as well.
Once you go far enough in to the normal Attacker/Defender and buffer you will unlock additional class's such as Tank, Berserker, Scout, Healer, Sp Buffer ... and more.
To Unlock Healer
Go To Lodend Mountains Norlangarth Empire.
For the Ex Healer... Healer Hands of the Gods skill Can be Unlocked by the statue.
To Unlock Debuffer
Go to Rivalier Forest in Norlangarth Empire.
Debuffer Skill Curse of the Weak can be unlocked in Sivila Mountains.
To Unlock Scout
Go to Cordea Plains lower right of the map on top of a Mountain will be sitting a statue.
To Unlock Tank
You must first Block 100 attack's then go to the stone in Sothercrois Empire -Warmia Greenbelt it will be in a cave called Spira Caverns. Just simply talk to the stone.
Tank Infernal Eye Skill Statue can be found at the Eastern Gate.
To Unlock Berserker
You must Successfully Execute 100 Skill Connect's and talk to the stone lakeshore area.
To Unlock SP Buffer
Successfully Use the required number of support skills on allies 50 time's In the Creyst Cove.
Domain of the Gods Skill Statue is found in Drugo's Temple area.