My mri report said redemonstrated is prominent csf space in the superior posterior fossa, unchanged. it is favored that this represents prominent subarachnoid space/normal variation rather than an arachnoid cyst.what does that mean?

Translation= the person assessing the study says its normal

Since you do not provide any data regarding reasons for the MRI, we have only your rendition of a radiologist's interpretation. An arachnoid cyst is a congenital variation of usually no consequence, and it appears that there is no cyst present, so, no structural lesion of any significance. NO Neurological abnormality was demonstrated and films are NORMAL!