Here's the explanation of value objects from Wikipedia:
"In computer science, a value object is a small object that represents a simple entity whose equality is not based on identity: i.e. two value objects are equal when they have the same value, not necessarily being the same object."
A very interesting aspect of value objects is their immutability - they are immutable objects.
As Wikipedia says: "In object-oriented and functional programming, an immutable object (unchangeable object) is an object whose state cannot be modified after it is created."
That means they have their final state after creation. A more than interesting concept for your software design. Therefore I wrote two examples in ABAP, inspired by the book "Clean ABAP".