1 ) go to this link 
  ( https://github.com/mojtabaRKS/laravel-persian-validation)  
2 )    and download the file 
3 ) and save it in this route 
   ( laravelProject\resources\lang ) 
   
   
4 )    now go to this route ( config\app.php ) 
5 )  and find the 'locale' => 'en'
6 )    and change it to this :  'locale' => 'fa'