Basic Gàidhlig sentence structure is Verb Subject Direct-Object. So the English "a dog is big" translates to "tha cù mor," literally "is a-dog big." English would use verb-first for many questions, i.e. "Is a dog big?" Gàidhlig instead uses words that, since I don't know the proper term, I call question-verbs. Thus: "A bheil cù mor?" Literally: "Is-indicating-a-question a-dog big?"
More complex present tense Gàidhlig verbs do not exactly translate to English present tense, but are closer to present perfect, which uses "is" and a verb ending in "-ing." Thus "A dog is seeing food" and "A dog sees food" both become "Tha cù a' faicinn biadh," literally "Is a-dog seeing food," which again has the same word order as the English question form.
I like to remember "Gàidhlig questions English," which reminds me that Gàidhlig declarative sentences use the word order of English questions.