I think it is called overloading. I'm not to sure what the first one is doing, but the second one is creating a new operator for the class A with the symbol =. This is done so that the members of the class can use that symbol in place of some more tedious operations.
Just to add on to what Smac said those are called the copy constructor and assignment operator respectively (The copy constructor is always around even if you don't define it but it doesn't handle dynamic memory allocation well).
Normally if you have one you are going to need the other seeing as they both handle assigning values to an object.
If you are reading a book on C++ then why are you asking what is it? I think the book contains an explanation what is it. So you behave yourself very strange.
Or you should read another book on C++ for beginners.