From Xojo Documentation
A Class can Inherit from another class to build on its public and protected properties and methods.
Inheritance a feature of object-oriented programming where you create a new class that is based on an existing class. The new class is called the subclass and the existing class is called the super class. The subclass "inherits" (and can thus use) all the public and protected properties and methods of its superclass.
You will not use the Inherits keyword directly in your code. To have a class Inherit from another class select it as the Super in the Inspector for the class.