An inference, put it simply, is a guess that one makes or an idea that one has or formed based on the (limited) information at hand. When you are asked to infer, or to make an inference, from a text, you are asked to read between the lines and reach a conclusion or deduce something on your own, since not all the information is available or made explicit.
Since the fragment is describing sundaes, banana splits and flavors, it can be inferred that the scenario described is an ice-cream parlor or an ice-cream shop.