You can read more about it in “socialism: utopian and scientific” by engels an eye-opening book to me. Really what made me fall in love with marxism. There’s also a really cool section about the “mark” at the end which isn’t that relevant to know really but I found it very interesting nonetheless. It’s a short book but well worth the read.

As for “work” I guess you can go with the physical definition of it, however since we are talking about society i went with a more common understanding of work as in energy spent to produce value. Making that concrete however gets us of course into the weeds of what value is, differences between use-value and exchange-value. So I just tried to sneak it past you 😅