Sometimes a defender has too many tasks. It tries to protect two pieces at once. In case of attack, the defender can save only one. And you can take the other. A piece with a double task is called an overloaded piece or an overworked piece. It is simply too busy.
Ask yourself this question:
Which enemy piece is doing two defensive jobs at the same time?
What do you have to do?
Make the best use of an overload and win material.