I remember you promissed to get rid of this word "mašiny" in the renewed course. Not that it bothers me or something, I am just saying. By the way - my Czech friend told me he would never use this word when referring to a mechanical device. He would only use it in order to describe someone who is so strong, powerful and durable he is "(like) a machine".
Using it to mean that someoone is strong/powerful/durable is weird. The closest usage I can think of is "Maká jako mašina" - "He works like a machine", to describe someone working with lots of endurance and power, but even that is not common. I can imagine someone who goes to the gym daily might say this about himself. Also note it has to be combined with the slang verb "makat", which already suggests hard work.
I would personally never (or rarely) use the word "mašina", it sounds dumb and machistic to me. Some Czechs do use it, however, and most frequently it refers to a motorcycle, just like in the song "Holky a mašiny" that VladaFu mentioned.
It is colloquial, but the tradition is long. This is from the 40s: https://bara.ujc.cas.cz/psjc/search.php?hledej=Hledej&heslo=mašina This from the 60s: https://bara.ujc.cas.cz/ssjc/search.php?hledej=Hledej&heslo=mašina They do say poněk. zast. and ob. so it is probably not suitable for the course, but it is here now and the course is frozen. The main reason it is here is the similarity with the English word.
Mašinka for a hair cutting machine is the most common spoken word for the appliance. "Vemte to na 3 mm mašinkou."
And, of course, the famous https://www.csfd.cz/film/5104-frigo-na-masine
"Those are the big machines" needs to be followed by something to justify the definite article, something like "Those are the big machines I told you about" - or such a followup is implied. Here the definite article also needs to be expressed in Czech - by a demonstrative. The Czech equivalent would be "To jsou ty velké mašiny" (...o kterých jsem ti říkal).
Well, you're supposed to learn what the sentence means and how it works.
- Those are big machines. = To jsou velké mašiny.
- Those machines are big. = Ty mašiny jsou velké. OR: Tamty mašiny jsou velké.
They are different sentences, used in different contexts. It's not just about phrasing anything the way anyone wants.
I am native AmE. Those sentences may ultimately make a very similar point, but they use different grammar to do it. They are not, in either language, "absolutely equivalent," and the course very consistently distinguishes between the two constructions. In my view, it is in our interest, as learners of either language, to get our heads around this. :-)