: This adds a second layer of security, such as a text code or authenticator app, making it much harder for hackers to use stolen credentials.
A combo list is a compiled database of usernames (often email addresses) and passwords harvested from various data breaches across the web.
Why hotmail.com stopped delivering to aol.com and yahoo.com.
: The "2020" likely indicates the year the data was leaked or compiled, while "install" may refer to the setup of a tool designed to process these text files for unauthorized access. History of Major Email Services