None. Some might claim that there is a symmetry about a vertical plane but the robin's left side will not be EXACTLY the same as its right side.
For example, the human face, although often thought to be symmetrical is not. One of your eyes is probably marginally higher than the other, your earlobes are unlikely to be exactly the same shape. As far as the interior is concerned, you are very lopsided: heart and stomach on the left (normally). Liver on the right. etc. The musculature on your dominant hand/arm will be slightly better developed. The differences may be too small to see with the naked eye but that does not mean they are not there.
However, in Biology, symmetry refers to the overall shape of the body and its parts, and is only approximate. Therefore, in terms of zoology, robins, like all vertebrates, have bilateral symmetry. This means they have symmetry across one plane (known as the sagittal plane, and directly down the centre of their body), which means one side of their body approximately mirrors the other side.
Lateral Symmetry.
Bilateral symmetry
bilateral symmetry
Radial Symmetry
turn symmetry
Bilateral symmetry.
Bilateral symmetry. All humans have bilateral symmetry.
Radial symmetry
An octopus has bilateral symmetry.
They exhibit bilateral symmetry.
radial symmetry
Radial Symmetry