What this meant was that language stopped evolving since last 2400 years ago. You can create new words but there are precise rules for it. All this means there is no scope for "dialects", words meanings changing with geography etc. Different vedic chants separated by thousands of miles and 1000 years in time are exactly the same and perfectly understandable in any part of the country for anyone who has studied Sanskrit.
This makes Vedic chants unlike anything English, Latin or Arabic has to offer.