The object depends on the return value of the join point.
If you don't call proceed(), the advised join point is bypassed. proceed() causes the execution of the advised join point, and it will return the same value returned by the advised join point. For example, if you are advising a method that returns a Person object, invoking proceed() will return the same Person object as the advised method.
So in the method you have you would do some stuff before the method was invoked, then you will call proceed(). At that point you have the result of the invocation of the advised method (the object). Now you can do some stuff after the method has been executed optionally using the return value. Once you return the object the original caller will get the result (object)