your sentence would translate as: هذا المطبخ أمريكي
Notice the change in the definite article AL. Without it (as in the sentence above) makes "kitchen" مطبخ as predicative - so in English, this word must come AFTER "is".
When adding "AL" to it, then this word combined with "this" are all together a subject for the sentence, and must come BEFORE "is".
Actually this is just a trick you can think of mentally while translating. I didn't want to go deep into grammar.