Don't confuse Spanish food with Mexican food. Although Spanish is ancestral to Mexican, Mexican food is heavily influenced by New World Indian foods like tamales and tortillas. Spanish food is more closely related to Mediterranean, African, and European cuisines.
Most Spanish food has two ingredients in common -- olive oil and garlic -- so it's fairly simple to find the basic necessities. Eggs, beans, nuts, eggplant, zucchini, chicken, lamb, pork, and beef are other easy-to-find ingredients typical of Spanish cuisine.