I have a follow up question about that.

I´ve seen (for example in "Teach Yourself Beginner´s Turkish") bunlar and þunlar with plural nouns, for example in one dialogue one person was pointing out to things saying: "... bunlar tuvaletlar, þunlar duþlar, o da bizim köpek ...".

Is it ok to use double plurals when you say "these are ..." or "those are ..."?

Which is more correct or common in usage for, let´s say "these are cars"? "Bunlar arabalar." or "Bunlar araba."?

Also, I think to ask "What are these?" one would use "Bunlar ne?". Is it also ok to say "Bu neler?"

Thank you.

As a learner you always think more than us and find different ways

So, as you said, it is only used when you are pointing, showing some things.

For example, you are the host and showing your guests:

"These are the towels and those are your beds"

this translates to "Bunlar havlular ve þunlar da yataklarýnýz"

But if you are only describing something you cannot use plural; you cannot say "bunlar arabalar" unless you are showing someone who asked for the places of the cars.

For "what are these?" you cannot say "bu neler?" correct way is "bunlar ne?"