We are discussing about Karm, Karta and Akarm. Karma can be divided in 3 parts. 1- Nitya karm , 2- Naimitik karma & 3- Kamya karm.
Nitya karm means, which we have to do for body and lifeliving. These are unavoidable karm. for this we don't desire any fruit, so, no karmfal is binding us. Yes , if you earn money with cheating or looting, then , that becomes AKarm & for that you Have to bare Karmfal .
2nd is Naimitik karm. = we have some reason to do karm. e.g. we see an old or weak person carrying heavy thing & we help him, then it becomes Naimitik karm. That act had motive after it. In these pendemic days, people donate food, clothes ,medicines,etc. to needy people. Now this donations called Naimitik karm. There is Nimita- reason-motive for that karm . This comes in the category of SWADHARM also .
Then comes , Kaamya karm . In this act , we our self create occasions. In this we do karm ,having some desire- kamnaa. People wish that there should be fame and name , so, wealthy person arrange great maariage function , some religious institution arrange Maha Ygna ; Political party leader will gather people for meeting, Dharna or Morchaa.So in all thes karma there is some or other wish is hidden. The karm done for having some fruit of it it ,becomes Kaamya karm .
There are 2 other karma also . Prayshchit karm -Repentance- In this ; when we come to know that something has gone wrong by us , ; we , repent for that and try to beg pardon from either God or go to the place or person to forgive . . This is called Prayshchit- repentance karm .
Lastly comes Nishiddha karm . The act , which should not be done at all . In this come gambling ,boundless enjoyment of senses, harming or hurting any being etc. These all are Nishiddha karm
Let's come again to shloka 20,21,23. Here in shloka 20th, I am going word by word. TYaktvaa= leaving-given up . What is given up ? "Karmfal aasangam"Aasangam= attechment ;of ,Karmfal= fruirful result .
Then comes "Nitya trupt"nitya= always , trupt = satisfied. "Niraashrya"simple meaning is without shelter. Here , who is not in the shelter of the senses,i.e. under the power of senses & who has no temptation of having pleasure of material life and who seeks God's blessings.
"karmani abhi pravrutth api " Apl= yet , pravruttah= who is engaged ,Abhi= deeply , Karmani= in action,Sah= such person , "KAROTI"= does karm NAiv= not doing karm .
The whole sentance of this shloka is --"Who has left the attechment of fruitful result, Who always remain satisfied in any situation, Who is not bounded with senses or swept with senses, Who does not seek pleasure in material happiness,but, seeks shelter of God only-YET, who is engaged deeply in action-pravrutti-karm; he\she practising Akarm,i.e. Akartabhaav.
IN21st , Krishna again repeat the same thing in other words; which we had read in 3rd. ch .also. He described the way of karm. HERE "Niraashi "without desire for fruit, " yad chitt aatma" Yad= who , "chittayma= controll over mind and intelligence,"tyakt sarv" = leaving everything-all senses of proprietership, storage of materials - "Aparigrah"like money, clothes, food And any type of biased thinking, jalousy, reveng feeling. IN short , collection of material and mental feelings.
Then comes, " Shaariram" = body ,"keval"= only ,"karm" = act , "kurvan"= does, "na" =not ,"aapnoti" = acquire ," kilbisham"= sinful reaction.
"Who has no desire for fruit, Who has controll over mind & intelligence, Who has left all senses of proprietership over possessions, and Acts only for the bare neccessity of life ( see here comes, Nitya karm ), that person; Though, do karm is not affected by sinful result.
Now, in 22nd Krishna shows what is "shaareeram kevalm karm "
"yad yacch"== out of its own, "laabh"= gains. means; person does not make endeavor even to maitain body , "Santushto",= who is satisfied with which he gains coming from his own accoed.
Then comes "dwandaateeto " = who is free from duality. who remains in same calm ness ,in "sukh-dukh, likes-dislikes, good -bad, in short in any situation stays "sthita"balanced minded. Then "Ateet" = free from duality. Then word comes, "vimatsar"= without envy Here the shloka says ,- " The person, who is satisfied with gain which comes without any endeavor, even to maintain body, and Who has surpassed duality. Going further, word is " samah" = steady . "siddhavsiddau" here 2 words are combind. Siddhi+asiddhi= succsses or failure. "krutvaa api" api= yet, krutva= does "karm"= acts, "nah"= never ." Nibadhyate " = not affected. Just like Lord Shankara . He ,who bismearing ashes, can anythig affect Him ? He is always "nitya santushta" ever satisfied. He does not need sheltter or He does not desire anything . Nothing affects Him. Like Him, person should do work.
So , the entire meaning is --" person who does not make endeavor to maintain body , Who is satisfied with which he gains coming from its own accord, Who surpasses duality,Who is steady ,Who does not have any effect of succssess or failure, IS never entangled by anything. means no "karmbandhan" ; though he performs action . This is Akarta bhaav,or AKARMA Akarma does not have meaning to be idle. "Vikarma, according to Vinoba Bhaave , means " Vishesh karma .when we do karm, with whole heartedly, with full love and feeling in mind , that , we are doing karma for God then , that karm becomes "vishesh karm - vikarma. And it is considered as Akarm .
In these Krishna teaches about Karma, Akarma and Akartabhaav. If stheer Aatm bhaav is there then no karm can bind us in "karm bandhan" Aatmbhaav becomes our raincoat which does not allow the drops of karma bandhan on us .
Thank you .