Why are you specifying Point point twice and why is 1 capital letters and one lower case letters?

When you create a method that takes a parameter you have to first define the type of the parameter and then the name. Point is the parameter type and point is the parameter name. The name could have been anything, it doesn't have to be point. But the type has to be Point because that is based on the class name.

You are telling C# that you are expecting to be passed a Point object and that it should be assigned to a variable called point. It is the same as if you set up a method that was expecting a string or an int. Except that instead of using built-in datatypes you are using a class you created yourself, which is also considered a type of data in C#.

While it can be confusing for beginners it is pretty common to name variables that will hold an instance of a class the same as the class itself (just in lower camelCase), though as I mentioned above that is not mandatory. You can use whatever name you find appropriate.