Portugal is one of the most linguistically homogeneous countries in Western Europe. But there still exists some interaction with neighboring Spanish. As well as one unusually unique language in the middle of the country.
Minority languages which are sometimes considered dialects have multiple possible answers
Note: The Galician speaking area I've drawn out in the top in some sources say speaks Portuguese and in others Galician. I could not find any definitive answers because the place is essentially deserted (probably less than 500 inhabitants). So I chose Galician to add a bit more diversity to the quiz.
Surely there can be a place with multiple unique languages, thus in that place a unique language wouldn’t be unusual. Meaning in a place like Portugal, an almost entirely linguistically homogeneous country, a unique language would be unusual.