A coffee name is given to the barristo/barrista when you order your coffee drink - you need a coffee name if your name is difficult to pronounce, or if your name is unusual. A coffee name expedites your order.
This morning I went to Starbucks for my morning latte. I told the clerk that my name is Antionette which he could not spell. So I used my coffee name: Toni. Much easier to pronounce. I have several friends & co-workers who use coffee names. When coffee drinks are delivered to us at work there's always someone who says: "Who's Dave?" "That's for Dwight - he used his coffee name."