There are many uses for Secrets. It could be as simple as your Mac is located in a different room to your wallet, so Secrets gives you the convenience of storing your Bank cards on your Mac and making online shopping a breeze. Or maybe you are always forgetting the passwords to the different online Web sites that you use and need a central place to store this information.
Because the information is encrypted on the computer, even if malicious viruses found their way onto your Mac, or villainous thieves stole your laptop, your information will remain safe. Only you, with your password can access this information.