Two Factor Authentication
Two factor authentication (2FA) is a good thing.
A password is secure, as far as it goes. Only you know it. So only you can log in.
But if someone else learns your password, they can log in. So you add a second factor. As well as something you know (your password) you need something you have in order to log in. This may be your mobile phone, or a small gadget to generate a passcode.
This is an especially good idea for any website that may cost you something - mobile banking, for example.