Looks like it means that the encryption cannot be reverse-engineered: http://help.penzu.com/pro/what-is-one-way-encryption/
So, a hash function and not encryption? Got it.
Sarcasm aside, we really need to start using the correct terms.
https://paragonie.com/blog/2015/08/you-wouldnt-base64-a-pass...
Cryptography
||\
| \`- Hash Functions
| `- Secret-Key Cryptography
| |\
| \`- Secret-Key Encryption
| `- Secret-Key Authentication
\
\
`- Public-Key Cryptography
|\
\`- Public-Key Encryption
`- Public-Key Authentication
Hashing is NOT encryption.So, asymmetric cryptography.
Encryption is a reversible, keyed transformation of a message. If you cannot reverse it, it is not encryption. Calling it encryption just introduces confusion.