An oval has two lines of symmetry. A line of symmetry is defined as the line that a figure can be divided into half, with the end result of the two halves matching up exactly. Each side of the divided side looks like a mirror image.
An oval figure can be divided down the middle, both lengthwise and vertical, with the result of the two halves matching each other. The oval cannot be divided on an angle other than straight across or up and down. This results in two halves that do not match up. Circles and some triangles are also symmetrical figures.