The extreme example is a struct converted to a class by adding accessor methods. Physical information hiding provides little or no help in isolating the effects of changes. If the hidden field changes type than one usually ends up changing the accessor methods to reflect the change in type. This abstraction can be manipulated independent of its underlying representation. Details are being hidden from the out side world.
Examples are integers and stacks.
We use integers all the time without knowing any detail on their implementation. Similarly we can use the operations pop and push without knowing how the stack is implemented.