JIRA uses Lucene, a high-performance text search engine library, in full-text searches for issues stored in JIRA. This option is designed to enhance JIRA's search indexing and issue searching features for issues entered in the languages available in this list. Hence, choose the language that matches the language used in your issues are entered in.
Choosing a specific language in this list has the following effects when conducting searches in JIRA (in with respect to your chosen language):
If multiple languages are used in your issues (or you wish to disable the two effects above), choose Other.
You will need to re-index JIRA if you change this value.
This section lists all language packs available within the JIRA system. (Note: to install additional languages, see Internationalisation.)
The language used throughout the JIRA interface (as selected from the list displayed in Installed Languages above). Users can override the default language by using the Language setting in their user profile.
Default user time zone
This is the time zone used throughout the JIRA interface. Users can override the default language by using the Time Zone setting in their user profile. (To choose the time format see Configuring the Layout and Design.)