normally translation need to do manually one by one but you can download language pack from prestashop translation page http://www.prestashop.com/en/translations . Through prestashop back office you can install language translation pack. Once you install language pack there will be 70% translate will complete and rest need to do yourself through prestashop back office. Last time we have done translate through google online tool but somebody says that google online tool is also not better to translate. In next version we will make translation for english, spanish and french language.