1. Check the Character set whether new language you are enabling is supporing or not?
2. Activate new language from License Manager from Oracle Application Manager
3. Check from the tables, new language is activated or not?
SQL> select NLS_LANGUAGE from FND_LANGUAGES where INSTALLED_FLAG in ('B','I');
4. Run Maintain Multi-lingual Tables from Adadmin
5. Run Maintain Snapshot information from Adadmin
6. Run the Translation Synchronization Patch utility (adgennls.pl) using below command
The manifest generated from the tool is located at : $APPL_TOP/admin/$TWO_TASK/out/adgennls.txt
7. After you generate your manifest, you can go to http://updates.oracle.com/TransSync (use your My Oracle Support username and password).
Follow the instructions on the screen to upload the manifest file. A Translation synchronization patch will be generated specifically based on your manifest for each of your active language. The patch will synchronize the language file versions and American English file versions in your Applications instance.
8. Install the Release 12 NLS Help for the new language (optional)