Str obviously is for fighter types. Makes you stronger to hit harder
Agility is for scouts, makes them dodge better and hit rate more accurate.
Wisdom is for gimpy Iksar clerics like me! :P J/K Wisdom is for priest jobs, makes your spells stronger and resistances to some things stronger
Intelligence is for mage jobs, makes their spells stronger.
I can't remember the others off the top of my head because I'm tired and it's really late, but basically...eh, it's common sense stuff. You want a warrior with a lot of Str, a priest with high Wis, etc etc. You don't want a scout with crappy Agi who's going to miss a lot. *shrug* the nice thing is, in this game...you can certainly make just about anything you want, because there are lots of items out there to help say... a gnome brawler or ....an Iksar Cleric. Just make sure you know what stats are most important to your job, and focus on those first when upgrading equipment.