I don't know about the language part, though. I'm neither Slovak nor Polish but can pretty much figure out what's been written about in a Czech or Slovak newspaper. Polish...not even close.
The spelling (and phonetics in general - the sounds letters or combinations thereof make, the accents used on the vowels, like squiggle vs dot) are different, but the spoken language is very similar. Though both Czech and Slovak lack nasal vowels (something Polish has in common only with French among Euro languages). Like they were converted to a written language by 3 different Roman scholars with wildy different opinions regarding best practices. I can totally understand both, and if I mix my Polish with some anglo phonetics, I can read Czech (don't think I've seen Slovak writing anywhere). It's a bit like British vs American English, except with no fetishization back and forth. When I went to Prague I was delighted to find I could get along easily (we crossed the boarder on the train from Frankfurt, and you immediately knew by the state of the farmhouse rooftops, but more importantly a young hipster dude with a confection cart came to our compartment, as opposed to the German Amazonian warrior that came a few minutes prior, and I could understand exactly what he said; immediately ordered a beer and a chicken sandwich). Czech sounds like a person with a speech impediment or brain damage speaking Polish. It took a day to realise the feeling was mutual; it was the face I got from the barista after I said 'please' ordering some cofee the next morning that clued me in. Slovak is even closer.
Ukranian or Russian, by contrast, is much harder, but I can mostly understand what Putin is saying if I really concentrate.
Incidentally, because I find this amusing to no end, Russian and American Rednecks have such a similar subcultures that they e independently developed the same idiomatic catchphrase. "Giv'r," is exactly the same in both literal and contextual meaning in both cultures, though otherwise completely unrelated words (sound nothing alike). From there it has crept into Polish (the word already existed, but this sort of colloquial usage).
So how is it you can read Slovak?
