can i change the language of the theme to arabic ?

Yes, that theme says that it’s translation ready. If there is not already an Arabic translation available for it, you can create one.

You might want to start with this page:

https://developer.wordpress.org/themes/functionality/localization/

and then take a look at these pages:

https://make.wordpress.org/polyglots/handbook/ (lots of good resources there)
https://codex.wordpress.org/Function_Reference/load_theme_textdomain

Let us know if you get stuck, and as always, be sure to include details about which system you are using.