How we can use ARRAYS in PL/SQL

How we can use ARRAYS in PL/SQL
Example for Arrays
declare
TYPE v_array IS TABLE OF emp.empno%TYPE INDEX BY BINARY_INTEGER;
a v_array;
b number:=0;
BEGIN
FOR I in 0..5 loop
b:=b+1;
a(I):=b;
END LOOP;
dbms_output.put_line(a(0));
END;
/