Go to: Login » Surveys (Select Survey) » Edit » Languages
Once you add a language, you will see the Import Translations left navigation menu.
Click to Download Import Template
Enter translations to this file and import this file back by clicking on Import Translations button.
Click on the preview icon to view the survey in the added language.
Language added for the survey will be automatically applied, where the respondent will get an option to select from the language if multiple languages are added.
This feature is available with the following licenses :