Translate homepage meta Title and description
You need to install the variable translation module.


  The Variable translation module, part of the Internationalization
  (i18n) package, allows you to translate text and settings that are
  stored in Drupal as variables. These variables include text such as
  'site name' and 'site slogan', as well as settings like 'Default front
  page' and 'Default 404 page'.


Go to 


  admin/config/regional/i18n/variable


and select the variables you would like to translate.
Then translate the string(s) at 


  admin/config/system/site-information