What is PUA/PUP
PUA is the abbreviation of Potentially Unwanted Applications, it also be named "PUP" - Potentially Unwanted Programs.
You can refer this page to learn How to use Windows 10 Defender to block Potentially Unwanted Applications.
These applications are not considered viruses, malware, or other types of threats, but might perform actions on endpoints that adversely affect their performance or use. PUA can also refer to applications that are considered to have a poor reputation.
Typical PUA behavior includes:
These applications can increase the risk of your network being infected with malware, cause malware infections to be harder to identify, and can waste IT resources in cleaning up the applications.
You can refer this page to learn How Microsoft antimalware products identify malware and unwanted software.