But if "эти кошки" is understood as a complete sentence, Landsend is correct and it does mean "These are cats." Эти is still an adjective-like pronoun as Olimo says, but now it is the predicate adjective following a linking verb.
With apologies to Crocodile Dundee: "You think those are cats? Those are not cats! These are cats!"
Note added 2 February 2017
I was a little confused when I wrote the above. "These are cats." is "Это кошки." I may have been confused by thinking about sentences such as "Те фигурки сабаки а эти кошки."
I found this helpful to get a sense of distinguishing between "this ----" and "this is a ----" for singular VS. plural and Fem. Vs Masc.
this cat. этот кошка. these cats. эти кошки. this is a cat. Это кошка. these are cats. это кошки.
this dog. эта собака. these dogs. эти собаки. this is a dog. это собака. these are dogs. это собаки.
Trusting google translate here!