Two-Step Authentication adds another layer of security to your account by texting you a validation code to enter whenever you log in or make important account changes.
After enabling this feature, you must enter a validation code every time you log in or make important account changes. If you log in to your account frequently or have multiple users managing your account, we do not recommend enabling this feature.
NOTE: At this time, only U.S.-based numbers can receive validation codes. This means your account's address must be in the United States (Settings > Account Owner Information > Country/Region) and your account's language must be set to United States — English (Settings > Contact Preferences > Language).
NOTE: Validation codes last for 20 minutes.