A namespace is almost like a folder that keeps scripts and classes from clashing with others that might have the same name. It's good practise to add them around classes which may have common names or specific use cases, so you can keep the code specific to your systems. This Padlock System uses the namespace: "namespace PadlockSystem" - you can reference this in other scripts to use the public methods in those scripts.
How to reference namespaces to use in other scripts?
If you need to access the padlock scripts from another script that isn’t in relation to this asset you may need to use a namespace collection at the top of your script: “Using PadlockSystem;”