What does it mean to have ovalocytes in a blood smear?

Depends: If hemoglobin level is normal, it does not mean anything. Some hemoglobin variants produce oval rather than perfectly round red cells and then it depends on the type of hemoglobin variant. A few ovalocytes are of no consequence.

Ovalocytes: Red cells varying in shape from elongated to oval, and rich in hemoglobin, are called elliptocytes/ovalocytes. They can be seen in hereditary disordrs, such as hereditary elliptocytosis, or in acquired disorders, such as iron deficiency anemia, thalassemia and in newborn babies.