Native IDE support of multiple languages
The primary language of the APEX IDE is English, and the initial APEX instance is installed in that language. However, the APEX IDE also supports a User Interface that has been translated into nine more languages German, Spanish, French, Italian, Japanese, Korean, Brazilian Portuguese, Simplified Chinese, and Traditional Chinese. Each of these languages can be loaded into the APEX IDE to transform the entire development environment mainly the UI, the internal messages of the APEX engine, and error messages to be displayed in the loaded languages. If more than one language has been loaded, then the language setting of the local browser will determine the language of the APEX IDE.
Note
Multiple APEX IDE languages don't mean multiple APEX instances. As we'll see in the APEX installation appendix, each database can only hold a single APEX instance. This rule still applies. We are talking about a single APEX instance that supports multiple APEX IDE languages...