Parcelona is a play on the words Barcelona a city in Spain and parcel a synonym for mail. It's funny because the mail man who delivers parcels is going to Spain. The second part is a joke on the word delivery as in a mail man who delivers mail and delivery as in how you pace and tell the punchline of a joke and it's the effect that has on someone understanding the joke and thinking it's funny.
You deliver packages as a mailman