Is Guam recognized as a U.S. address or foreign address?

Are you referring to a civilian address as opposed to a military type address (APO, FPO, DPO)?

If so, Guam is a US territory.   You didn't say what screen you are on, so I'll assume you are in the Personal Info section on the screen to enter your address to show on your tax return.  

For civilian,  "Type of mailing address" you can choose U.S. Territory in the dropdown menu, then the fields will change.    Then a little lower down is another box that says "U.S. territory".  When you click the box or arrowhead there, you'll get a dropdown menu with a list of US territories.  You should see Guam in the list.

@csquinata 

You didn't say anything about your Guam situation and what all you are trying to do in regard to Guam.   Depending on your circumstances, TurboTax may or may not be able to do everything you need.   I'm not a tax expert, but if you explain more about your situation, I've asked a TurboTax Tax Expert to assist you here on explaining any ramifications for Guam.

@JohnB5677  (thanks)