Let’s say you walked into a store & wanted to ask if they had something available, but you don’t know how! Well, now you can! The verbs that will come in handy here are 있다 (itda) & 없다 (eopta).
있다 & 없다 are the infinitive/dictionary forms for the verbs ‘to have’ & ‘to not have’. So if you wanted to ask them, “do you have food?” you would say ‘밥 있어요?’ (bab-iss-eo-yo). Remember, the 요 makes it formal, so if you were asking your friend if they had food, it would simply be ‘밥 있어?’
Now let’s see how the store clerk would answer you. If they did sell food, they would reply with ‘밥 있어요’. It’s the same exact thing except they are not asking in question form! If they did not sell food, you would use the verb for ‘not have’. So they would reply with ‘밥 없어요’ (bab-eops-eo-yo).