Entombed has a unique and fun job system that allows enormous variety. Generally speaking, your character's job is what they're primarily good at. A job defines a number of skills, abilities, and magic that your character can use.
In addition to your primary job, once your character reaches a certain level, they can choose secondary job too. You can set your secondary job on the character menu (key C in-game).
A second job grants your character all the skills and abilities of that job, but there are a few caveats. For one, second jobs don't receive any armor or weapon skills. Second jobs don't affect the stat growth of your character.
For example, lets say you choose Fighter as your primary job and Healer as your secondary. Your character will inherit the spells and abilities of the healer job and you'll be able to use all the weapons and armor that a fighter grants. However, your magic points won't grow as fast as if you had chosen a spell caster primary job and your intelligence will suffer.
Alternatively, lets say you choose Healer as your primary job and Fighter as your secondary. Your character's magic points will grow quickly and you'll be very intelligent, but you wont receive any of the Fighter weapon or armor skills. Your Healer / Fighter can use Flurry though – which is an exclusive Fighter ability.
Using this system you can create a vast array of different characters with drastically different strengths and weaknesses. In all, there are over 350 possible combinations!
Note: Not all jobs are available from the on-set. You may have to discover how to unlock them. Some jobs are only available in the full version of Entombed.