Oracle DBMS_OUTPUT

The Oracle DBMS_OUTPUT package enables you to send messages from stored procedures, packages, and triggers.
DBMS_OUTPUT contains the following procedures: DISABLE, ENABLE, GET_LINE, GET_LINES, NEW_LINE, PUT, PUT_LINE.

DBMS_OUTPUT.PUT_LINE

DECLARE
c varchar2(200):= 'This is a DBMS_OUTPUT.PUT_LINE test';
BEGIN
DBMS_OUTPUT.PUT_LINE (c);
END;

Result: This is a DBMS_OUTPUT.PUT_LINE test

DBMS_OUTPUT.NEW_LINE

DECLARE
c1 varchar(25) := 'test_1';
c2 varchar(25) := 'test_2';
BEGIN
dbms_output.put_line(c1);
dbms_output.new_line;
dbms_output.put_line(c2);
dbms_output.new_line;
dbms_output.put_line(c1);       
END ;

Result:
test_1 
test_2
test_1