It can be used, only with IMPDP. This helps in generating the DDLs from a dumpfile.
Suppose I have dump file of table DBACLASS.DEP_TAB . If you need the DDL of the table, then use SQLFILE with IMPDP command as below.

This will not do the actual import. It will just dump the metadata (DDL) of the table in the specified .sql file.

parfile will look as below:

dumpfile=test.dmp
logfile=test1.log
directory=TEST
tables=DBACLASS.DEP_TAB
sqlfile=emp_tab.sql

impdp parfile=impdp_sqlfile.par
 
Import: Release 12.1.0.2.0 - Production on Mon Jan 23 15:14:16 2017
 
Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.
 
Username: / as sysdba
 
Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
Master table "SYS"."SYS_SQL_FILE_TABLE_01" successfully loaded/unloaded
Starting "SYS"."SYS_SQL_FILE_TABLE_01":  /******** AS SYSDBA parfile=impdp_sqlfile.par
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/STATISTICS/MARKER
Job "SYS"."SYS_SQL_FILE_TABLE_01" successfully completed at Mon Jan 23 15:14:22 2017 elapsed 0 00:00:01

Now check the sqlfile(emp_tab.sql):

cat emp_tab.sql
 
-- CONNECT SYS
ALTER SESSION SET EVENTS '10150 TRACE NAME CONTEXT FOREVER, LEVEL 1';
ALTER SESSION SET EVENTS '10904 TRACE NAME CONTEXT FOREVER, LEVEL 1';
ALTER SESSION SET EVENTS '25475 TRACE NAME CONTEXT FOREVER, LEVEL 1';
ALTER SESSION SET EVENTS '10407 TRACE NAME CONTEXT FOREVER, LEVEL 1';
ALTER SESSION SET EVENTS '10851 TRACE NAME CONTEXT FOREVER, LEVEL 1';
ALTER SESSION SET EVENTS '22830 TRACE NAME CONTEXT FOREVER, LEVEL 192 ';
-- new object type path: SCHEMA_EXPORT/TABLE/TABLE
CREATE TABLE "DBACLASS"."DEP_TAB"
   (    "OWNER" VARCHAR2(128 BYTE),
        "OBJECT_NAME" VARCHAR2(128 BYTE),
        "SUBOBJECT_NAME" VARCHAR2(128 BYTE),
        "OBJECT_ID" NUMBER,
        "DATA_OBJECT_ID" NUMBER,
        "OBJECT_TYPE" VARCHAR2(23 BYTE),
        "CREATED" DATE,
        "LAST_DDL_TIME" DATE,
        "TIMESTAMP" VARCHAR2(19 BYTE),
        "STATUS" VARCHAR2(7 BYTE),
        "TEMPORARY" VARCHAR2(1 BYTE),
        "GENERATED" VARCHAR2(1 BYTE),
        "SECONDARY" VARCHAR2(1 BYTE),
        "NAMESPACE" NUMBER,
        "EDITION_NAME" VARCHAR2(128 BYTE),
        "SHARING" VARCHAR2(13 BYTE),
        "EDITIONABLE" VARCHAR2(1 BYTE),
        "ORACLE_MAINTAINED" VARCHAR2(1 BYTE)
   ) SEGMENT CREATION IMMEDIATE
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
 NOCOMPRESS LOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "USERS" ;
-- new object type path: SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
-- new object type path: SCHEMA_EXPORT/STATISTICS/MARKER

This method can be used to get DDL of any type of object(INDEX, TABLE, PROCEDURE, PACKAGE ETC) from the dump , without actually doing the import in the database.