Let us now look deep into what are objects. If we consider the real-world, we can find many objects around us, cars, dogs, humans, etc. All these objects have a state and a behavior.
If we consider a dog, then its state is - name, breed, color, and the behavior is - barking, wagging the tail, running.
If you compare the software object with a real-world object, they have very similar characteristics.
Software objects also have a state and a behavior. A software object's state is stored in fields and behavior is shown via methods.
So in software development, methods operate on the internal state of an object and the object-to-object communication is done via methods.