Yes, the Central Station Passcode is a word used in alarm situations when the Central Monitoring Station calls to verify an alarm. You create the code during initial system setup but can easily change it whenever you want.
The following support document details how to update this, should you ever want to change it:
Safe word is the same as "Central Station Passcode". I have to keep mine written down somewhere because I can never find it. And I've only had to use it once or twice. You will find it in the small gear icon on your xfinity home web page.