Attempts to safeguard you against gold scams from malicious scripts involving social engineering
The related chat exploit was already fixed by Blizzard (to some degree)
If you do actually run the script, it will warn you, temporarily block trades and /reload your UI to remove the script
This does NOT help against WeakAuras (they are pretty safe now) or any malicious addons
But I suppose being aware about suspicious scripts from shady strangers is already enough protection by itself
Related: SDPhantom created a
virtualized environment for script commands