I looked it up, having not read it before. It's the idea that many modern jobs seem pointless, even to those doing them. They feel unnecessary or redundant, leading to stress and a sense of worthlessness. Graeber argues employment is being valued for its own sake, rather than for meaningful contributions to society. He feels productive ones, like teaching or healthcare, have clear and positive impact. Lots of stuff about how culture and beliefs about work might be encouraging the existence of these unfulfilling jobs.
Mostly, but not exactly. Graeber would have probably identified a number of jobs in both Healthcare and teaching as BS jobs (e.g. pulmonologists who largely treat smokers who don't have good addiction support as duct tapers, or assistant principals in bureaucratic schools as task masters).
Except that teaching and healthcare are some of the least productive sectors in the economy, which is why they're seeing steadily increasing costs over time. Suggesting that no rent-seeking or socially wasteful effort is occurring in these areas is quite ludicrous.
