More high-level skills like "people" skills, "conversation" skills, and things like that. They're not specific to individuals or individual languages but are general and more about concepts rather than specific examples.

People skills and conversation skills are also what I typically associate with "soft skills", but it doesn't seem to make sense when applied to (maybe half of) those books?

Yes, the poster is using "soft skills" in an idiosyncratic way.

That's a great way of saying "incorrect"

It's also a good example of "soft skills".

I assume they mean things like

  * Thinking like a programmer
  * Planning projects
  * Working with others
  * Time and project management
  * Setting up your environment

etc.

Yeah, all those things that are unimportant until you have to work with other human beings.

CPR is important, but I don't want to read about that when I'm taking a course on hiking and camping.