They're making conversation.
My job, the only people who understand what I do are people who do what I do. I work in IT and I just tell people I work with computers because it's what people associate with that. Really though while I can do the computer repair stuff, I actually work with servers, cloud storage, network cores, HVAC systems and things like that.
My husband is Cardiologist, I have no idea how he does the things he does. I know he does stents, pacemakers, balloons and other procedures but really I don't know how it's done or how he decides that's what the person needs. He told me once all the veins he could get on a single picc and I just took his word for it because I didn't know any of them. Everyday when I ask him how his day was, I get the same answer "busy". If I ask something specific he will explain it, but it's usually long and winded and really I'm not that invested in it. I also work at a hospital and I asked him once what a "stemi alert" was and I got the really long medical definition of it and told him to feel free to dumb it down like I was 5 and got "heart attack". You know who understands what he does? Other doctors.