Workflow Language Setting

SELECT
    L.NLS_LANGUAGE ||'_'|| L.NLS_TERRITORY ||'.'||NLS_CODESET NLS_LANG_CODE,
    L.NLS_CODESET NLS_CODESET,
    L.LANGUAGE_CODE CODE,
    LTL.DESCRIPTION DISPLAY_NAME,
    L.NLS_LANGUAGE NLS_LANGUAGE,
    L.NLS_TERRITORY NLS_TERRITORY,
    L.NLS_CODESET NLS_CODESET,
    DECODE(INSTALLED_FLAG, 'B', 'Y', 'I', 'Y', 'N') INSTALLED_FLAG
  FROM
    FND_LANGUAGES L,
    FND_LANGUAGES_TL LTL
  WHERE
    LTL.LANGUAGE_CODE = L.LANGUAGE_CODE
    and DECODE(INSTALLED_FLAG, 'B', 'Y', 'I', 'Y', 'N') = 'Y';
1. Define NLS_LANG Environment Variable on your PC, following below navigation:
For Windows
Start / Settings / Control Panel / System / Advanced / Environment Variables
Define new "System Variable" NLS_LANG and assign it the value from NLS_LANG_CODE in he first step.
Save
NB : the above assumes language AMERICAN is installed in the database. It could be replaced by any other installed language, for instance FRENCH_FRANCE.WE8MSWIN1252 if French has been installed.

2. Re-start the PC as needed.

3. Try again database connection from the Workflow Builder.