In Serenytics, the application's language (e.g. for the left menu) and the dashboards' language (e.g. for dynamic filters entries such as "select all", "unselect all") is stored as a user's property. You can change it in the "Account" section. If you're an admin user, you can set the language for all the users in the "Admin" section.
For embedded or public dashboards¶
When a dashboard is public or embedded, the dashboard is loaded without any Serenytics' user logged. By default, the dashboard language is English. But you can specify the language as a dashboard property. To do that, open the dashboard in the editor, open the 'Layout & Print' section and set the dashboard language.