make me understand the below code
DATA: BEGIN OF line,
col1(1) TYPE c,
col2(1) TYPE c,
END OF line.
DATA: etab LIKE TABLE OF line WITH HEADER LINE,
ftab LIKE TABLE OF line.
line-col1 = 'A'. line-col2 = 'B'.
APPEND line TO etab.
MOVE etab[] TO ftab.
LOOP AT ftab INTO line.
WRITE: / line-col1, line-col2.
ENDLOOP.
output is : a b
what is table of line refers to
begin of line
col type c
col2 type c
end of line // this is header line