I know of no standard term for that aspect of PL. Maybe you can use "human-readable syntax" or "human-friendly syntax".
In PL theory, we (unapologetically) tend to disregard syntactic issues (e.g., look at LISP), and focus more on language features / semantics / types and more math-y stuff.
I mean: if you asked me what are the main differences between C++ and Python, I would probably spend a long time before mentioning some syntactic difference.
For practical applications, of course, having a more human-centric design that the one offered by pure theory is important. A clean and easy syntax is certainly quite convenient to read and write.
Note that, if a PL pushes this principle to extremes, and employs a syntax which is very close to natural language, it could possibly harm productivity. This is because, natural languages can be quite ambiguous, and when programming you really need to be rigorous. Trying to oversimplify a PL by completely removing the math-y aspects of PL is probably not a good idea.
COBOL is arguably more human-readable than Python, but it's hardly better.
x = y+z is simpler than
ADD Y to Z GIVING X.