BGR writes that you can now use Touch ID on your iPhone to sign in to your Google account via 2-Step Verification (2FV).
Usually, 2FV consists of inputting your username and password (step 1), and then entering a code that is sent to you via e-mail or a text message, or even via an authentication app or machine (step 2). Now, however, Google has added a new option for iPhone and iPad owners, with the new “Google prompt” setting added to the 2FV settings. To use it to log on to your Google account, all you have to do is select “Yes, Allow Sign-In” when the notification pops up on your device. While this option is available for all iPhone and iPad owners, regardless of whether or not they have a Touch-ID-enabled iPhone or iPad, the whole process is now even easier for those that do have a Touch ID device, as you can use fingerprint authentication via the Google app to log on to your account.
Source: You can now use Touch ID on your iPhone to sign in to your Google account anywhere