Binance Jersey is the Fiat Exchange of Binance. So you can buy and sell Bitcoin and Ethereum for Euro. The name Jersey comes from the fact that the exchange is based on the English island of Jersey.
If you want to trade at Binance Jersey, you have to create your own account on the platform, your normal Binance account will not work as a login. You will also need to verify your identity in order to deposit and withdraw funds from Binance Jersey.
The disadvantage of Binance Jersey is that only 2 crypto currencies (Bitcoin and Ethereum) are currently traded against Euro. If you want to trade other crypto currencies you have to buy Bitcoins or Ethereum from Binance Jersey and then transfer them to Binance.