When you sign in on the web, you can choose to trust your browser, so you won’t be asked for a verification code the next time you sign in from that computer.
your password and the six-digit verification code that's automatically displayed on your trusted devices
You need at least one apple device. When you sign for the first time in via a browser on Windows, the verification code is sent to your apple device. Once you enter the code in the browser, you can choose to trust the browser. BTW, the first time you log in with a browser on Windows, it can be tricky. I'm pretty sure I signed up with Firefox, and the verification never worked. I had to sign in with Chrome for the verification to work.
Note: Quotes taken from the link provided in the first post.