A 'final' class cannot be subclassed. Frame the concept in practical terms so you can explain it during interview discussion.
In Java, marking a class as 'final' means no other class can inherit from it. This is useful for classes that are complete and should not be extended, like utility classes. For example, Java's 'String' class is final to prevent modification of its behavior.
Additional Notes
What does declaring a class as ‘final’ mean in Java?