You often have to enter a security code when you log in to an account from a new location or device - that's two-factor authentication! It's an extra piece of information that you need to provide before you get access to your accounts. In addition to your login and password, it's further proof that you are you.
Set up YubiKey in Dashlane in 3 easy steps.
Turn on two-factor authentication in Dashlane.
Add your YubiKey to Dashlane.
Plug in your USB key and go!