There are several places that you could visit on Christmas Eve, depending on your location and the time of day. Here are some ideas:
Grocery stores or convenience stores: Many grocery stores and convenience stores will be open on Christmas Eve, and they may have a limited selection of last-minute items for Christmas dinner, as well as some gifts and decorations.
Gas stations: Gas stations will also be open on Christmas Eve, and they may have some basic snacks and drinks available if you need them.
Pharmacies: Some pharmacies will be open on Christmas Eve, and they may have some basic medical supplies or over-the-counter medications.