Exactly what I was taking about in the other thread about this section. Tą vs tę. Good to know that if I go to university there I can tell the difference but can keep it to myself when talking to peeps.
"zupę" is the Accusative case, used for the direct object of the sentence. We have no sentence here and no verb that could take a direct object. This is just a phrase without any context, so it takes Nominative - the basic form, which is "zupa".