"The worker talks about his job."
Translation:Robotnik mówi o swojej pracy.
Swój is used when the possesive pronoun refers to the subject of the sentence (and not to some different person).
"Robotnik mówi o swojej pracy (=his own job).
Robotnik lubi chwalić swojego syna. Teraz opowiada nam o jego pracy. (=the son's job).
There may be some differences if you make up some specific context but basically that's all you need to remember. PS For those who know Swedish/Danish/Norwegian it works exactly the same as sit(t)/sin.
You may want to check out this post. I couldn't find any discussion about this particular topic there but maybe you'll find some other helpful explanations.