Something that is symmetrical has corresponding similar parts: in other words, one side is the same as the other.
If you can draw a line down the center of something and get two similar halves, it’s symmetrical. Shapes like squares and circles are symmetrical. Unless you've had a serious injury like losing a limb, the human body is symmetrical. Some people think that faces that are more perfectly symmetrical are more beautiful than other faces. On the other hand, an eye patch tends to look kind of cool, even though it makes a face unsymmetrical.