This anonymous quote likely came about to encourage those who are literate to read more. However, the skill–reading–can be replaced with any other skill or talent.
We’re all blessed with different talents, or there are certain skills we’ve developed over the years. Yet while being capable of talents and skills is praiseworthy, they don’t mean much if they’re never applied. This quote encourages us to use our talents and skills. After all, when they’re never used, we’re at no more of an advantage having them compared to someone without them.