So you’ve got this sentence, and it’s made up of two things an an action. We shall call the action like thing a function, or a predicate, drawing on influences such as Math and Logic, and along this vein, the things shall be called arguments. This is relatively commonplace in Linguistics.
In English, this would go something like this.
(1) Sven kicked a puppy
What information do we get from this sentence? We know there is a puppy, and as well, an action of kicking, and somebody names Sven. As well, we know that the one doing the kicking was Sven, and the one being kicked was the puppy. How do we know this? To a speaker of English, I have basically asked a trivial question. In a sentence of English, the subject comes before the verb, and the object comes after the verb, in unmarked sentences*. We call this SVO word order. In an unmarked sentence of English, those components always go in that order. However, were I to look at an unmarked Klingon sentence
(2K) puq qlp loD
(2) man hit child
(2E) The child hit the man
Now, while it excites my inner nerd unleash what limited knowledge of Klingon I have, this is not my reason for going to Klingon. I have to go to Klingon for an OVS language, because of the languages we have on Earth that have been investigated, only a few have been posited as having an unmarked OVS order, and none of them is not somewhat controversial. However, there seems to be no a priori reason why the Klingon word order is impossible for English to have taken. In all, there are 6 word orders
SOV – Latin, Hindi, Japanese, Navajo
SVO – English, French
VSO – Formal Arabic, Welsh, Tagalog
VOS – Malagasy
OSV – Arabic
OVS – Klingon, some controversy over other languages.
How this is done is no real mystery, in those languages, the subject, object and verb all have their relative positions, and you identify which is which by word order. There is an unmarked word order in The Old Tongue, and it is SOV. However, when it comes to Argument Agreement, this is not the whole story…
*Let us leave aside the question of what an unmarked sentence is, and for now, and rely on some wishy-washy notion that an unmarked sentence sounds normal, whereas a marked sentence requires some untangling. For example, put the verb and object first, I may, although sound like a native speaker, I shall not. And in fact, Yoda does just this, with the effect that he sounds somehow separated from language, more aloof and all-knowing and all that. But no native speaker of English hears Yoda’s speech and says ‘ah yes! This is precisely the way I would have phrased it!’ (or, ‘ah yes! Phrased it this way, I would have’, for that matter.