Can you please specify the link of the extension that support multilingual site in magento2
It is an out-of-box feature: http://devdocs.magento.com/guides/v2.0/config-guide/bootstrap/mage-run.html
Actually you may not need an extension to make 2 language website in Magento 2.
It can be done through separate store view, store or website within the same Magento install depends on the differences required between language versions
Dmity is not trying to convince you to use his extension.
Dmitry, please change your signature so that it can be clearly identified as one. Right now it looks like a part of the message.
Can you please suggest a plugin for this to implement both English and Arabic language in my site.
You do not need a plugin. Magento can do this by default. Just create a second store view and give that store view a different language.