Two-step verification is an optional feature that adds more security to your account. When you have two-step verification enabled, any attempt to verify your phone number on WhatsApp must be accompanied by the six-digit passcode that you created using this feature.
To enable two-step verification, open WhatsApp > Settings > Account > Two-step verification > Enable.
Upon enabling this feature, you can also optionally enter your email address. This email address will allow WhatsApp to send you a link via email to disable two-step verification in case you ever forget your six-digit passcode, and also to help safeguard your account. We do not verify this email address to confirm its accuracy. We highly recommend you provide an accurate email address so that you’re not locked out of your account if you forget your passcode.