There are several places in TurboTax where one might enter an address, and you didn't specify "where" you are trying to enter one. The main address for the return is entered in the Personal Info section, but there may be additional forms asking for address as well when you go through the interview.
In general, if you are trying to enter a "foreign address", you first select the "type" of address as "foreign country" in the dropdown menu for that field. Then the remaining fields will change. You will then see fields for Province and Country.
If that's not it, then you need to explain fully where you encountering the issue and in what situation.
Are you completing a Canadian tax return?
This is the TurboTax US user community website.
Go to this TurboTax Canada website for assistance with a Canadian tax return or the TurboTax Canada editions - https://turbotax.community.intuit.ca/turbotax-support/en-ca