Data Redaction is one of the new features available in 19c. Data Redaction is in Advanced Security option of enterprise edition.

Oracle Advanced Security Data Redaction provides selective, on-the-fly redaction of sensitive data in SQL query results prior to display by applications so that unauthorized users cannot view the sensitive data.

OFSLL application processes sensitive data. Hence, it is recommended to use a Data Redaction to protect confidential data, such as credit card and social security numbers, stored in table columns.

There are different types of redaction; full, partial, regexp, random and none. Please refer Oracle® Database Advanced Security Administrator's Guide, section on Configuring Oracle Data Redaction Policies for details.