There are 17 skills in FOnline: 3. The skills you want to pick depends on who you want to become (Warrior, Crafter, Doctor, Wanderer, e.t.c.). The percentage of the skill shows how good you are at that skill. Each time you level up, you will gain some skill points. You can spend these points to increase your skills. Note that fewer skill points are required to increase the three skills you tagged when you registered the character. Note that weapon skill is a major factor determining your Chance to hit.
This lists all of the skills, and each ones' limit.
In the case of combat skills, Related Perks are many, and some are specific to certain weapons rather than the all of the weapons in that class. See next section for popular choices.