The terminology is vaguely defined. In the mouth of a techie, I'd assume they mean "everything that gets studied but isn't STEM or business", with a connotation "and is therefore easy since it doesn't have a rigorous grading system".

There are links between Renaissance humanism and what is now called "humanities". The Humanists weren't just about the re-naissance of Greek and Roman works, but also about creating new ones. A lot of humanists were poets, painters, and writers -- fields often lumped in with "humanities". There was also a rebirth of what the Greeks called philosophy, which also included subjects that we'd call sociology (laws, ethics, forms of government, etc.) Sociology is also treated as adjacent to humanities.

Techies do need to learn that the easily-measurable aspects of a technology are not the only important ones. We use tech because it appeals to us as humans, using the yardstick of our perceptions of things. Humanities are easily dissed because they're hard to measure objectively, but that doesn't mean they're unimportant. Indeed, they may be more important precisely because we haven't (yet) learned them well enough to be simple.