Emotes are animations that can be triggered by the player's input in the chat box, sending a message on the Emotes channel or by selecting from Player Menu. Emotes can't be used while in combat or mounted. If you're targeting anything, the emote's message will mention its name. For example, if you type /wave while targeting a player named Target, it'll say "Player waves at Target".
List of Emotes
To see a list of all available emotes, type /emotes.
Using every emote unlocks the Emotional achievement.