By enabling 2-step verification on your G account, you can add an extra layer of security. With verification enabled, whenever your Google account is accessed from an unknown computer, login will require an extra step, or second step in order to successfully sign you in (text message verification).
To get started, navigate to Google.com/settings/security and select the Edit button next to 2-step verification.
From here, Google will prompt you to enable 2-step verification and setup your phone.
Note: You will not have to enter a code from your phone every time you sign in to Google. The only time that you will be required to enter the pin, is when you Google account is accessed from an unknown computer, location or IP address.
"Ways 2. Enable 2-step verification --Secure your Google Account"
Reference : online-tech-tips.com