First of all make sure that you have installed language pack from http://www.prestashop.com/en/translations . If you unknow how to add language pack in prestashop . Please follow this blog https://blog.devilthemes.com/language-translation-in-prestashop-1-6/
This image slider is developed by prestashop team.
To translate each slider image you need to choose desire image and click on edit button
Select language option to change according to you language. and save it. You can change picture,description and link according to your.