Your family will provide breakfast before class; you are responsible for any further meals yourself. Please let us know about any special dietary requirements, and discuss your preferences with your hosts, to make it easier to accommodate your taste.
There are restaurants nearby which offer noon-time specials, as well as bakeries, grocery stores, and other shops. You also have access to the Mensa (cafeteria) at the University of Heidelberg. In the evenings there are numerous options for eating out. Heidelberg has a huge selection of restaurants that will suit any taste, and any budget.