分 (fen) means "hundreth". The coin is worth 1/100 of the main unit, which is the Chinese yuan (not the jiao). Still today, the CNY is divided into 100 fens.
It works the same way as the US cent, which is worth 1/100 of a US dollar.
Another reason why I think the WC is incorrect, is because it considers as cents all the other coins in fen.
For instance, Y#355 has the same lettering as the Y#347 but is written "CENT (1 Fen)".
Similarly, Y#348 reads "5 fen" and it is considered as a 5-cent coin.
The WC's confusion is probably due to the pretty big size of this coin. Later 1-fen coins were reduced in size.