This feature is never to scare away its users but rather to make sure they have a safe WhatsApp account. WhatsApp is rolling out two-step verification to all of its billion-plus users, after debuting the feature in the beta version of the app last year.
The verification step can also be known as two-factor authentication, this optional feature adds an extra layer of security to users’ accounts.
To enable it, users need the latest version of WhatsApp and should then navigate to Settings > Account > Two-step verification > and Enable. Once this feature is turned on, users will have to enter a six-digit passcode every time they register their phone number with WhatsApp again. So, for example, if you get a new phone but keep the same SIM card and number.

WhatsApp’s authentication steps isn't like Facebook which generates a code with an app or sends one text message. You’ll have to remember your WhatsApp passcode, or you can set up a backup email, which will allow you to disable two-factor on your account if you ever forget your six-digit passcode. You can also disable two-factor from within the app, without a passcode.
And although you won’t need to use the passcode every time you open the app,

WhatsApp will ask you for it at a given time interval inorder to make sure you remember what it is.
Info source; http://www.premiumstech.com/2017/02/WhatsApp-is-rolling-out-two-step-verification-to-all-billion-plus-users.html?m=1

Them done come again with their foreign monitoring spirit