I canít find out what it means here (nothing in Longmanís Dict. Of English Idioms):
Coins are small and easy to carry, which is more than you can say about cows or elephants.
A couple of examples would be appreciated.
It means that you can't say that cows and elephants are "small and easy to carry".
In other words, the phrase is true of coins, but not of cows and elephants.
"...which is more than you can say about X..." is a mildly humorous expression.