"Our house is in this country."
Translation:Наш дом находится в этой стране.
You can use the choice "наш дом в этой стране " (without "находится") as well for this sentence. in Russian, when you say that something exists, then it implies "находится" and you don't have to use this word.
"Наш дом в этой стране" can mean "our house in this country ..." (without "is") that means in Russian "we have many houses in different countries and we are talking about one of them" . The particular meaning depemds on a context.
But "наш дом в этой стране" is more widely-used than the another one with "находится".
"Страна" is feminine, so you should use "в этой стране", but you can use "в этом госуда́рстве" = "in this state".