Have you registered the MFA for this account before? If yes, make sure you sign-in on https://aka.ms/mfasetup to recover your MFA token. Once you recovered the MFA token with the authenticator app, you will be able to sign-in again.
If you are not able to recover your MFA token by yourself, you'll need to contact the owner of your tenant to reset your MFA. If you are the owner, make sure you sign-in with a global administrator account to reset your other business account.