Amer Melebari

the idea of the plugin from <a href="http://wpaon.com/?p=48" rel="nofollow ugc">this post</a>
bascally the plugin generats two functions you can use them in your theme
the functions are: 
1. comments_number_ar(‘لا توجد تعليقات’, ‘تعليق واحد’, ‘تعليقان’, ‘% تعليقات’, ‘% تعليق’ ); 
2. comments_popup_link_ar(‘لا توجد تعليقات’, ‘تعليق واحد’, ‘تعليقان’, ‘% تعليقات’, ‘% تعليق’ );
the functions are similar to functions comments_number () and comments_popup_link () 
I just edit them to be correct with Arabic grammare.
<ul>
<li>For more information http://6efy.com/blog/?page_id=2222</li>
</ul>

Arabic Comments Number

this plugin allow you to display the number of comments with Arabic grammar

SiMULA

A WordPress plugin developed by <a href="https://simulalab.org" rel="nofollow ugc">Simula Lab Ltd</a> that gives the admin(s) of an Arabic site the possibility to use Levantine Arabic Month Names in WordPress dates instead of (or in combination with) Modern Standard Arabic month names. It also allows for using Arabic-Indic numerals instead of Arabic numerals in WordPress dates and time.
It allows the site to:
<ul>
<li>use Arabic-Indic numeral (١, ٢, ٣) instead of Arabic numerals (1, 2, 3) in WordPress dates and times.</li>
<li>use Levantine Arabic months names instead (شباط, آذار) of Modern Standard Arabic months names (فبراير, مارس) in WordPress dates.</li>
<li>use a mix of Levantine and Standard Arabic months names (شباط/فبراير, آذار/مارس) or (فبراير/شباط, مارس/آذار) instead of Modern Standard Arabic months names.</li>
</ul>
After installing and activating the plugin, navigate to the “Settings” menu in the Admin Dashboard and select “Levantine Dates”.
The plugin has no effect on non-Arabic sites.

Simula Levantine Dates for Arabic Sites

A plugin that add options to use Arabic-Indic numerals, and Levantine months names in dates and times to Arabic WordPress sites.

Arabic Comments Number vs Simula Levantine Dates for Arabic Sites