If your code was complete - which it isn't, it's missing a close bracket, then ...
.something" refers to a field, method or property of the current class instance called "something", in the same way that "my car glove box" would reference to the specific glove box on your car, and have no interest in the content of the glove box on that car over there, you know - the grey one.
So if you put your mobile in the glovebox of your car and then come out in my car with me, you don't expect to find you mobile in my car's glove box - my car is a difference instance of the class of "cars" from your car.
refers to the specific instance you are working with at the moment, and
refers to the current car's glove box.
When you provide a parameter of the same name though, you access that without
because you are talking about the specific value that the method was called with rather than a property of any specific class instance.
See here: What is the use of self in Python? self in Python Class Example | Edureka