Upon initial setup of Two-factor Authentication (2FA), you will receive 10 recovery codes for your use. If you begin to exhaust these codes, a notification will appear prompting you to generate additional codes.
To do this, select 'get a new set' within '2FA' on your account:
You will then be presented with a screen displaying your newly generated recovery codes:
Save a copy of these codes and store them somewhere safe. If you lose access to your authenticator app, you can use your single use recovery codes to sign in to your account.
Please note: without these codes you may lose access to your account.
If you've used all your recovery codes and can see a message like the one below in your account, you'll need to generate new codes as soon as possible before you can log in again using the recovery code method:
Select 'get a new set' and you'll have 10 new recovery codes generated.
As per the advice above, save a copy of your codes and store them somewhere safe.
If needed, two-factor authentication can be accessed from your account profile screen, which you can get to here