This plugin controls the language of Jenkins
Normally, Jenkins honors the browser's language preference if a translation is available for the preferred language, and uses the system default locale for messages during a build. This plugin allows you to:
This feature is sometimes convenient for multi-lingual environment.
Under Manage Jenkins > Configure System there should be a "Locale" section.
Here you can enter the "Default Language": this should be a language code or locale code like "fr" (for French), or "de_AT" (German, in Austria).
This value will be used by the system, for example, for messages that are printed to the log during a build (assuming that the Jenkins features and plugins that you're using have been translated into the specified language).
To additionally force this language on all users, overriding their browser language, you can check the "Ignore browser preference and force this language to all users" option.