In addition, support is provided for a locale model in which users can specify their language and formatting preferences to have the application delivered in the style that is the most useful to them. This model includes delivering to different users, simultaneously, the same application in multiple languages with different formatting.
Information about localization applies only if your version of the application has been localized.
Data language and display language
If all your users work and communicate using a single language, the data language and display language that they use are the same. However, if you have users in different locations using the same server (for example, users in England, France, and Germany), you must pick a common data language in which the users will enter and search for data. Typically, this data language is the most common across all your user locales.