Create table of numbered words.

create table words ( 
  word_no integer,  
  word    varchar2(10) 
)

Insert first row into table.

insert into words (word_no, word) values (1, 'Hello')

Insert second row into table.

insert into words (word_no, word) values (2, 'World')

Create log table.

create table log (
  change_date  date,
  word_num     integer,
  old_word     varchar2(10),
  new_word     varchar2(10)
)

Create trigger.

create or replace trigger log_change_to_word
after update on words 
for each row 
begin 
  insert into log (change_date, word_num, old_word, new_word)
  values (SYSDATE, :old.word_no, :old.word, :new.word);
end;

Change first row of table.

update words
set word = 'Bonjour'
where word_no = 1

Change second row of table.

update words
set word = 'Monde'
where word_no = 2

Display log table.

select * from log