"My house does not have a yard."
Translation:Nhà của tôi không có sân.
Something Huy_Ngo said on a different question forum was something to the effect of... A negative phrase like this can't have một unless you specifically mean you don't have "one" yard. If you write một and you don't mean specifically "one," then it has to be followed by something but I can't remember what it was.
Edit: I found what he actually wrote, I'll copy it here:
In Vietnamese negative sentences, if you say "một" you also have to say "nào cả" (không có một biên giới nào cả), because if you say "không có một biên giới" it will mean "does not have one border" (likely there are more than one)