A fob, sometimes called a key fob, is a security hardware device that some banks mail to customers when they first set up their online banking. These devices, sometimes in the form of a keychain or a usb drive, feature built-in authentication mechanisms that are used to control and secure access to online bank accounts. The fob typically produces a randomly generated access code that changes every 30 to 60 seconds. If the bank's website recognizes this code, the user gains access to their online banking.
As you might imagine, these sophisticated security systems prevent third parties, such as GoDaddy Bookkeeping, from being able to access these accounts.
If your fob is preventing you from being able to link your account(s) in GoDaddy Bookkeeping, please look on the bright side: Your online banking security system is awesome!