To set up two-factor authentication on WhatsApp, follow these steps:

1. Open WhatsApp and go to “Settings”.
2. Tap on “Account” and then “Two-step verification”.
3. Tap “Enable” to turn on two-step verification.
4. Enter a six-digit PIN code that you will use to verify your identity when setting up WhatsApp on a new device or after a certain amount of time has passed since you last used the app.
5. Confirm the PIN code by entering it again.
6. Optionally, you can add an email address that can be used to reset your PIN if you forget it.
7. Tap “Save” to complete the setup.

Once two-step verification is enabled, you will need to enter your PIN code whenever you set up WhatsApp on a new device or after a certain period of inactivity. This helps to protect your account from unauthorized access and keep your messages and calls secure.

Note that if you forget your PIN code and did not set up an email address for recovery, you may be locked out of your WhatsApp account and lose access to your messages and contacts. Therefore, it is important to remember your PIN code and/or set up a recovery email address in case you need to reset your PIN.