need to understand the execution plan of a query

Hello ,

Please refer to the below execution plan.Please advise why these extra fields are coming in execution plan(Pstart,Pstop,TQ,IN-OUT and PQDistrib)and what does this mean?

Execution Plan

Id	Operation	Name	Rows	Bytes	Cost (%CPU)	Time	Pstart	Pstop	TQ	IN-OUT	PQ Distrib
0	UPDATE STATEMENT				81240 (100)
1	UPDATE	F_ENGAGEMENT_PERSON
2	PX COORDINATOR
3	PX SEND QC (RANDOM)	:TQ10000	145	6815	81240 (2)	00:18:58			Q1,00	P->S	QC (RAND)
4	PX BLOCK ITERATOR		145	6815	81240 (2)	00:18:58	1	229	Q1,00	PCWC
5	TABLE ACCESS FULL	F_ENGAGEMENT_PERSON	145	6815	81240 (2)	00:18:58	1	229	Q1,00	PCWP

Back to Plan 1(PHV: 1931325571)
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Full SQL Text

SQL Id	SQL Text
bgqp3bkxw05mu	UPDATE DWADMIN.F_ENGAGEMENT_PERSON SET CLIENT_KEY=:2, HARD_START_DATE_KEY=:3, HARD_END_DATE_KEY=:4, SOFT_END_DATE_KEY=:5, IND_PRACTICE_GROUP_KEY=:6, ENG_EXPERTISE_ATTRIBS=:7, TAXONOMY_TERM_GROUP_KEY=:8, FUNCTIONAL_KEYWORD_GROUP_KEY=:9, FUNC_PRACTICE_GROUP_KEY=:10, PRELIMINARY_CHARGE_CODE=:11, LAST_MODIFIED_DATE=NVL(TO_DATE(:12, 'YYYY-MM-DD HH24:MI:SS'), SYSDATE) WHERE PROJECT_KEY=:1