Different langaguages are different.
OTOH, I disagree with the basic premise of the article. It is my belief that one shouldn't learn a new language to improve ones job prospects, but rather to improve ones skills as a programmer. So if you know C++, then you don't learn C# or Java, but rather Eiffel, Lisp, or Haskell, or possibly OCaML.
OTOH, If you already know C++ or Java, it's certainly easier to learn Python or Ruby. So easy that a basic knowledge can be learned in a day. So if you're tight on time, that will allow you to expand your capabilities in small increments. (But a basic knowledge won't teach you the libraries, which is where the important differences lie.)
FWIW, I first learned Fortan, actually FORTRAN, since it was before Fortran 77 was standardized. But then I went on to Snobol, PL/1, etc. I never did really master LISP1.5, but I didn't have access to a running implementation. With Lisps a decent IDE is nearly a necessity to start with. (Currently, if you want to pick up a lisp, I'd recomment Racket Scheme from PLT. It's got a decent development environment.)
OTOH, I dropped C++ about 20 years ago, and am no longer fluent in the modern dialect (something I keep meaning to correct). My current favorite language is D (Digital Mars D, or dmd), before that I cycled between Ruby and Python. Before I retired I normally wrote in whatever my employer chose, which, towards the end, was MSAccess Basic...a really foul language. So foul I wrote routines in Eiffel that did the work and just used the MSAccess Basic as a driver. Not only was it faster to write, it was also faster to execute, and unlike MSAccessBasic, the programs wouldn't arbitrarily start failing after a few months of use. (In the AccessBasis I used to need to save the programs as text files so that I could re-import them after the system corrupted them. Figuring out that there wasn't actually anything wrong with the programs took a lot of quite furstrating debugging, since a newly entered program would work properly. It's my guess that the system was storing some invisible binary code in with the source, so the source became unusable when the code got corrupted...why the code ever got corrupted I never found out, but it happened repeatedly to many different programs.) I presume that MS has by now fixed the problem, but it persisted over at least 5 years and multiple different versions of MSAccess.