You are informed that you've just gained XP by a floating bubble with the amount of XP. The status window shows a progress bar with the XP remaining to reach the next level. For each XP level gained, you have a skill point. Skill points allow you to learn jobs and use special skills. Skills are a great way to improve your fighting performances, but they also offer new gameplay opportunities, especially with non-fighting secondary jobs like swordsmith, armorer, ...
