I just want to say that the sentence was written in a difficult way (kinda old)...I think it is better to start with more simple paragraphs

م أخذت تتقارب هذه اللهجات وتتوحد بتأثير اجتماع العرب في مكة واجتماعهم في الأسواق والمواسم حتي جاء الاسلام ونزل القرآن الكريم تلغة قريش.= and this dialect getting to rapprochement and unit in the infuence of united of Arabs in M'aaka and their meeting in the markets(Assoik) and the (spicial,)seasons until the coming of of Islam and the descent (=/ cilmb) of the Holy Qoran

اعتقد ان هناك خطا "البينان" = البيان !!!? والعرب =and the Arabs هذا النوع من البينان = this kind of binan( statement,or " explication in words" =bayan ,بيان ! ') العرب أقدر من غيرها من الأمم = Arabs can more than other nations,(Arab nation have the ability more then the other natio ... بلاغة =Rhetoricns 1)=and Arabs able of this kind of statement more than the other nations wich is unmistakible(not abondement)in her rhetoricns to( some) this one. والعرب أقدر علي هذا النوع من البينان من غيرها من الأمم التي لا تخلوا بلاغتها من شيئ منه

And the Arabs to appreciate this kind of Alpinan of other nations that have not abandoned him something of the eloquence. but i don't know what you mean by البينان

Arabic language originated in the Arabian Peninsula, a difficult language because too many meanings And to be able to groove with reading elqur’an