The 3 most significant columns in the plan table are named OPERATION,OPTIONS, and OBJECT_NAME.For each step,
these tell u which operation is going to be performed and which object is the target of that operation.
Ex:-
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TO USE EXPLAIN PLAN FOR A QRY…
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SQL> EXPLAIN PLAN
2 SET STATEMENT_ID = ‘PKAR02′
3 FOR
4 SELECT JOB,MAX(SAL)
5 FROM EMP
6 GROUP BY JOB
7 HAVING MAX(SAL) >= 5000;

Explained.

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TO QUERY THE PLAN TABLE :-
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SQL> SELECT RTRIM(ID)||’ ‘||
2 LPAD(‘ ‘, 2*(LEVEL-1))||OPERATION
3 ||’ ‘||OPTIONS
4 ||’ ‘||OBJECT_NAME STEP_DESCRIPTION
5 FROM PLAN_TABLE
6 START WITH ID = 0 AND STATEMENT_ID = ‘PKAR02′
7 CONNECT BY PRIOR ID = PARENT_ID
8 AND STATEMENT_ID = ‘PKAR02′
9 ORDER BY ID;

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STEP_DESCRIPTION
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0 SELECT STATEMENT
1 FILTER
2 SORT GROUP BY
3 TABLE ACCESS FULL EMP