Single-Factor Authentication (SFA) is a process for securing access to a given system, such as a network or website, that identifies the party requesting access through only one category of credentials.
The most common example of SFA is Password-based authentication. Password security relies on the diligence of the system administrator or user who sets up the account. Best practices include creating a strong password and ensuring that no one can access it.
Source: https://searchsecurity.techtarget.com/definition/single-factor-authentication-SFA