At every level divisible by three (level 3, 6, 9, 12, etc.) you gain a single extra skill rank that can be placed in a skill of any ability. This rank is in addition to the normal number of ranks that you gain every level. This placement must follow the other usual restrictions (a maximum number of ranks equal to your level). This allows your character to branch out into a few new skills at higher levels that he would normally be prevented from.