The Fauns footed it all round Caspian to their reedy pipes.

1. "The Fauns" - In mythology and in Narnia, Fauns are mythical creatures with the upper body of a human and the lower body of a goat.

2. "footed it" - This is an old-fashioned expression meaning "to dance" or "to move one's feet in a lively manner."

3. "all round Caspian" - This means the Fauns were dancing in a circle around Caspian, who is one of the main characters in the book.

4. "to their reedy pipes" - Fauns are often depicted playing pipes or flutes made of reeds. This phrase indicates that the Fauns were playing music on these instruments while they danced.