Two-step verification is an authentication process that increases the security of your account.
How to enable Google's 2 step verification:
Download and set-up the Google Authenticator app on your mobile phone
If you are logging in from China and do not have access to Google Play Store the Google Authenticator app is available from Baidu app store. http://shouji.baidu.com/software/10010832.html
Click on the User Information icon
Click on Security
Click on "2-factor authentication"
Click "Generate QR Code for 2-step verification" button on your computer screen
Use the Google Authenticator app on your mobile to scan the QR code directly from your computer screen
Enter the 6-digit Authenticator Code within the time limit
Once 2-factor authentication is enabled, please review and update your security rules
Check the boxes on the right column for actions taken under your account that you want to use two-factor authentication. Don't forget to insert your current password to submit the changes.
Logout, then log back in to apply the new changes