Just how Ghost PII works is a bit technical but that doesn't mean you need to be a rocket scientist to use it. The core of Ghost PII is an API, maintained by Capnion, that provides you with specialized encryption keys for doing homomorphic computations (computations on encrypted data) on personally identifiable information like name, social security number, etc.
In a prototypical use case, the first thing you should do when you obtain personally identifiable information is call Capnion's API for an encryption key. Once the data is encrypted correctly there is no way to lose it to an attacker unless your system and Capnion's suffer total breaches at exactly the same time, and Capnion's system is designed both with top priority given to security and conservative data governance.
Imagine that that down the road you need to compare encrypted addresses, perhaps out of concerns that two addresses only differ in a superficial way like replacement of "Road" with "Rd." or similar abbreviation. You can then request a specialized key that will permit you to compute the number of characters that two encrypted addresses have in common without any need of decrypting.
This has many benefits. You never need to decrypt, which improves security. You have cut out the time and computational resources you might have spent on de and re crypting, which saves money and time (which is also money). You do not need to know for sure what kind of entity resolution you want to do down the road when you encrypt, nor do you need to grant the analyst examining duplicated addresses permission to see this personal information, and these break down the opposition between security and convenience. Ghost PII is a pure win for your business because it essentially eliminates a hard tradeoff, one that has forced many businesses to work with plaintext in the past.