Hovering over an skill icon will display the name, description, target, cast time, cooldown, and trigger rate, as well as any requirements such as a melee weapon. The lower left corner can be checked to display only the highest level of each learned skill.
Passive skills are automatically used once learned. Some are auto-learned but most must be purchased from a Skill trainer.
The Emotes are listed under that tab, and the Actions under its tab. Clicking on the Chains arrow opens the Skill Information Window.