SMS Two-Factor Authentication is a security measure clover.com uses to better protect your merchant information and ensure that only the people you choose to give access to your business’ web dashboard can access it.
After you enable this feature, you will need both your password and your phone to log in to your account. When you log in to your Web Dashboard you will receive a text message with a login code.
IMPORTANT
We strongly recommend all merchants use two-factor authentication to secure their business, transaction, employee, and customer information.
Reference Site: https://help.clover.com/faq/what-is-sms-two-factor-authentication-why-is-it-important-for-logging-into-my-clover-web-dashboard/