To put it simply, Arabic sentences are divided into two main types: "verb" sentences (first word is a verb) and "noun" sentences.
Verb sentences are structured as (from right to left of course):
verb > subject > object
Each word ends with a different short vowel depending on its place in a sentence. The subject for instance always ends in a dhamma ('u' sound), while the object ends in a fatha ('a' sound).
Unlike with the English language, rarely do you find someone who follows grammatical rules in everyday speech. Only scholars or teachers who use formal language apply such rules when speaking or writing.
The vastness of the language is also why Muslims resort to a tafsir (or explanation) of the Quran to understand certain verses and chapters. Words sometimes mean something else when found after a certain word or in a certain context.