The action bar is a shortcut to many of the commonly used emotes in There.  Also, if you have the voice feature enabled, you can turn it on and off from the action bar. 

To find the action bar, look to the lower left hand side of your client (There) window.  You will see a button that says "People".  When you click on "People", a menu will appear, and this is where you will find the toggle for the action bar.