If you read the help file on hotkeys it says right there what needs to be done, you need to learn how to search.
Ill give you the part you need.
This is usually only necessary if the script uses the Send command to send the keys that comprise the hotkey itself, which might otherwise cause it to trigger itself. The $ prefix forces the keyboard hook to be used to implement this hotkey, which as a side-effect prevents the Send command from triggering it. The $ prefix is equivalent to having specified #UseHook somewhere above the definition of this hotkey.