Let's look at these English sentences:

Kay sees the cat.
Mr. Park reads a book.

Notice that these sentences have a particular order. The subject comes first, followed by the verb, with the object at the end. (See note)

We can't change this word order without changing the meaning or producing a bad sentence:

The cat sees Kay.
Mr. Park a book reads.

English relies heavily on word order to let us know which part is the subject or object. It also uses word order to cue us in to whether something is a statement or a question:

Mr. Lee has cooked the rice.
Has Mr. Lee cooked the rice?