This may get a bit technical, but here goes:
"There is" is not written in Arab, but you might argue it should be there in English.
In English, we use "There is..." to introduce a new indefinite object into a conversation (i.e. "a car" that is new to the discussion versus "the car" which was already established at an earlier point in time). The word "There" is semantically empty in this construction, i.e. it does not indicate location as such, but only exists because English declarative sentences grammatically require at least one constituent to precede the verb.
In this particular case, you could also topicalize (i.e. 'move to the front') the location: "[Behind the house] is a car." The word "there" is no longer required, because the verb "is" is now preceded by another constituent. Notably, however, this does subtly change the meaning, because we are now emphasising the location of the car rather than the existence of the car.
I am no native speaker of Arabic, but from what I have seen so far, هناك functions exactly the same as "There is..." in English, and as the example above shows, topicalisation of the location is equally possible in Arabic (.خَلْف اَلْبَيْت سَيّارة). Therefore, it seems to me that this word order also emphasises the location خَلْف اَلْبَيْت over the car's existence; compare هناك سَيّارة خَلْف اَلْبَيْت . This would mean this sentence should be translated as "Behind the house is a car.", but it would be good if a native speaker could confirm.
i would guess سيارة خلف البيت but that is not a full sentence,just like in English.If you wanted to say the car behind the house is nice,then you would say السيارةُ خلفَ البيتِ جَميلةٌ . I too am learning Arabic,and i have a lot of similar questions like yours ( which got me thinking ),but in truth you can paraphrase a sentence to say what you mean,I dont know how efficient it is to quell yourself with the thought-and how do i say this?and to be too meticuluos,speaking in general.