I'm trying to eliminate other users from seeing other users SS in list group. Is there a formula that I can write in the Validation settings for that Column?
OOTB SharePoint does not have away to secure a column in a list, I think that this is what you are trying to achieve. There are third party products that provide this functionality, SharePoint Boost Column Level Security for example. Another idea would be to have a second list with the SS in it, then you can permission that list more securely.