The fewer words you use, the more powerful the message of a sentence is.
We'll learn how "the boy's dog" or "the dog of the boy" is expressed in Arabic. While in English the word "of" is used to express something in Arabic no word is needed. In English the suffix apostrophe "s" could be used instead, but in Arabic no extra attachment is necessary.
How does Arabic avoid using a word or a suffix like English does to express what this lesson is about? Well, it makes use of word order that would be non-sensical in English.
الولد means the boy (el-walad) كتاب means a book (kitaab)
In Arabic these two words, believe it or not are all you need to make a sentence. Yet, this lesson is about making a sentence fragment.
كتاب الولد the boy's book (kitaabU el-walad[i]) If we look at it word for word. The first part is kitaab' which translates to "book". The second word is "el-walad" which translates to "the boy". So a word-for-word translation might be: book the boy
That doesn't make any sense in English. to fix it up we'd have to add "of". So that it becomes "book of the boy".
the boy's book (kitaabu el-walad) [kitaabulwalad] كتاب الولد
the girl's book (kitaabu el-bint) [kitaabulbint] كتاب البنت
the boy's chair (kursiyyu el-walad) [kursiyyulwalad] كرسي الولد
the girl's chair (kursiyyu el-bint) [kursiyyulbint] كرسي البنت
the book's owner (saahib el-kitaabi) [saahibulkitaab] صاحب الكتاب
the notebooks's owner (saahibu el-daftari) صاحب الدفتر
the man's book (kitaabu el-rajuli) كتاب الرجل
the woman's book (kitaabu el-mar'äti) كتاب المرأة