When you enable Two-factor authentication, you are provided with an option to 'Trust the computer' or 'Trust the device'. You can choose to trust the computer or device, you do not have to enter the Two-factor authentication security code every time during a sign in.
You can view your trusted devices, add trust or remove trust from the web app:
On top right, click on your profile picture (or initials if profile picture has not been setup) and select 'Security'.
You will see computers and devices that have been active on your account or are currently signed in.
Click on 'Trust' if you would like to trust a computer or device.
To remove trust, just click on the (x) alongside the computer or device