The Keywords feature allows you to be notified whenever someone mentions a specific keyword in their text. For example, you can be notified whenever someone says your name. To configure this, open the Listener configuration by right clicking the minimap button and clicking Settings.
The configuration panel is self-explanatory enough, but the gist of it is that you can enter in keywords that are comma separated. Some of the keywords may be substitutions, for example "<firstname>" translates to your character's first name in their RP profile.
Enabling Keywords will cause any instances of them found to be colored and trigger a notification sound.