Need Help on understanding PL SQL and Database Trigger

TRIGGER

1.) does it use pl sql language?

2.) old.COLUMN_NAME. is old a syntax? is that the original value? im assuming that to get the user updated value we will just use the COLUMN_NAME?

3. can anyone explain the statement below? what does the quotation mark do?

CREATE OR REPLACE TRIGGER SIEBEL.S_TEMP_ORG_EXT
AFTER UPDATE OF "PASSWORD", PR_ADDR_ID, PR_CON_ID, CUST_STAT_CD OR DELETE
   ON SIEBEL.S_ORG_EXT   

FOR EACH ROW

4.) what does colum do? :master_ou_id

5.)what does updating do? UPDATING('COLUMN_NAME') what does UPDATING without the () do?

6.) what does WHEN OTHERS THEN do?