WPML
WPML is a multi-lingual translation plugin and provides the facility to translate WordPress, Themes, and Plugins strings and add contents in multi-language.
WPML is a commercial plugin. So, you need to purchase a copy of WPML, with the below modules, to start the translation.
- WPML String Translation
- WPML Translation Management
- Advanced Custom Fields Multilingual (ACFML)
Please refer to WPML documentation for detailed information about how to set up and use it.
Here are a few other WPML guides/document links which can be helpful.