Your Gmail account can be protected with 2-step verification (which is the same as two-factor authentication, 2FA). This means that you add an extra layer of security to your Gmail account. For the second step, you can use Nexus Personal Mobile, which is an application for online two-factor authentication (2FA). Once set up, you sign in to Gmail with your Gmail password and a one-time password (OTP), sent to your mobile device.
Other mobile apps for online two-factor authentication are, for example, Google Authenticator or Microsoft Authenticator. Nexus Personal Mobile offers extra security compared to them since you also authenticate your self in Personal Mobile with a PIN code or your fingerprint before you receive the OTP.