Two-factor authentication is a great security measure that helps to keep your Google account and information a little safer. I recommend everyone to turn it on, as your email account generally stores some of your most sensitive personal information.
Unfortunately this security precaution makes the process of setting up your Gmail account in Outlook a little trickier by requiring you to use an app-specific password for certain applications when you set them up.
Step 1: Click your profile icon at the top-right of the window, then choose the Google Account option.
Step 2: Select the Security tab at the left side of the window.
Step 3: Choose the App passwords option under Signing into Google. You will likely be prompted to enter your Google password on the next screen.
Step 4: Click the dropdown menus under Select the app and device you want to generate the app password for and choose Mail and Windows Computer, then click the Generate button.
Keep this window open, as we are now going to open Outlook and will need to come back to get this password in a minute.