Eelf,
I think you mean on the right side. By convention, when transverse cuts are made, they are viewed as if the examiner is standing at the patient's feet. So, the bright white spot is actually located on the patient's right side.
The fact that the mass is not bilateral is concerning. However, it is also hard to determine exactly where it is coming off of with so few images.
However, it does not compress, or invade, or shift the tissues of the cerebellum. Which is good.
Since it is bright white on this sequence of images (which appear to be T1, but can't tell for sure), that means that it has a very high content of water in it. It could be fluid, fat, or blood.
As stated, you usually like to see things mirrored on the body, ie bilateral. But, not all abnormalities are necessarily bad.
You should discuss this with the physician who ordered the study. All findings have to be correlated with the patient's history and examination to determine their significance.
Good luck.