"Telewizor" is the TV set (the electronic device). "Telewizja" (with "z") is the broadcast system and industry. So, you could say "Oni nie oglądają telewizji, bo nie mają telewizora" = "They don't watch TV, because they don't have a TV set" (note that the second "oni"="they" is omitted in the Polish sentence; actually the first could be omitted as well "Nie oglądają telewizji, bo nie mają telewizora" since the form of the verb implies who is doing the action).
Correct me if I'm wrong, but I believe this means TV as the medium (they cannot watch the channels), not that they do not own the device. So it would be "Nie mają telewizji".
As I often mention to help understand the distinction, I own a TV set (the device), but I can only watch DVDs on it, as I don't have any channels.
We often say things like "we don't have television" instead of "we don't have a television" (not using the article as we are referring to the feature rather than the object, though the meaning is the same). As Polish (per my polish wife) does not have a term for the "feature" of TV, I'm not sure if the translation requires an article in this case.
What do you mean by "As Polish does not have a term for the "feature" of TV"
oni nie mają telewizora= they do not have the electronic device called "telewizor", ( a device shaped like a box with a screen that receives electrical signals and changes them into moving images and sound)
"Oni nie mają telewizji" they do not own a TV station, or they live in a place where TV signal cannot be received.
telewizja= the method or business of sending images and sound by electrical signals
It's perfectly understandable, it's used sometimes (rather in writing than in speech), but I would only use it for "television" as the medium, the broadcasting, than the device.
If you're asking about accepting it in the English answers, yes, you can write "They do not have a TV".
Polish TV (phon. te fał) stands for television (telewizja), that is TV technology or TV service.
The TV abbreviation is not used to describe a/the TV set in Poland.
RTV abbreviation is commonly used in a phrase referring to the RTV (Radio and TV) equipment (sprzęt RTV/sprzęt radiowo-telewizyjny).
shortening - tłuszcz cukierniczy, tłuszcz do pieczenia, smalec, ceres