What does the LANGUAGE component of the NLS_LANG parameter control?
The language component of the NLS_LANG parameter controls the operation of a subset of globalization support features. It specifies conventions such as the language used for Oracle messages, sorting, day names, and month names. Each supported language has a unique name; for example, AMERICAN, FRENCH, or GERMAN. The language argument specifies default values for the territory and character set arguments. If the language is not specified, then the value defaults to AMERICAN.