The RCon is the remote console usable with many games built on source, such as Garry's Mod, Team Fortress 2 and Counter Strike: Global Offensive.
Usually, the RCon allows you to run commands on your server remotely, however, as it's not as common to use rcon anymore, we block it on our firewalls. Furthermore, we use rcon for internal purposes and you may be prompted to set/change the password for it if needed. Simply follow the guide below to get setup.
Side note, within the web console, there's a save box which allows you to automatically input the rcon password every time you open it, we suggest using it with your long, secure password for rcon.