Hi, this docs will help you to understand how you translate any language string by localise extension. We explain all step by step:
1.) Install your language first
Here we installing German DE language.
Language install successfully
Extensions > Languages > Content Languages after install the language you must need to activate from
2.) Install Localise Extension
Download the localise extension from Joomla Extension Directory then install it.
3.) Start Translate the Extension, Module ect
Go to components > Localise > Translation
Filter and find the extension language file ( For example we search for shortcode) If you want to translate roksprocket, you have to search for roksprocket
Look the language file (de-DE) look this
Click on file name and start your translation: