Murderbot uses "do the thing" as a euphemism for killing people, which Farai picks up on. When Murderbot leaves to go deal with the transit station milita vs. Barish-Estranza situation, it again says it's going to "do the thing."
The first time, it ends up cuffing the would-be attackers and hijacking their aircraft. The second time, it appears to save a train and a boat, then dip out of the situation—nobody witnesses what it does to the B-E team at the underwater dock.
In chapter 13, Sofi suggests that Murderbot can "do the thing"—but she's referring to it being able to hack a transit system that's locked to hotel residents so they can hitch a ride. She knows what "do the thing" means! It means Go Be A SecUnit!
From Murderbot's perspective, Murderbot is a deadly killing machine, deployed for violence. From Sofi's perspective, Murderbot is a superspy, a MacGyver or a James Bond, or maybe the team from Leverage or Oceans 12—a person who can do anything inside or outside the bounds of the law!
And Sofi is, of course, right :)
