2FA - Two factor authentication, you get asked a second secret besides your password. Banks used to give users a card with codes that you had to find and input when authenticating with them.
OTP - one time password, you receive a code over SMS or mail.
TOTP - Time based one time password, you have to have an authentication app that creates a clock based cryptographic code.
FIDO2 - fast identity online standard version 2, is a set of ID verification technologies. Usually you’re asked to confirm access on another certified device. Like google asking you to check your phone for a notification when logging into a new browser.