All interfaces (in the COM sense) have only functions that you can call. Functions correspond to the Methods of Visual Basic. Many interfaces also have special get and put methods. In this case, you can assume they refer to properties (corresponding to member variables of C++ classes). For example:
If an interface Picture has a get method called Size then you can use Picture.Size to refer to the property instead of calling a method.
If there is a put method then you can assign some value to Picture.Size. If there is only a get method. then Picture.Size can only appear on the right side of an equation in Visual Basic.