Understanding file paths or file locations in SAP DS

I am using SAP data services 4.x. Please see the image below -

When I set location = local instead of Job Server, then see folders and files to select from. But, when I select Job Server, I get these weird $ symbols which if I remember correctly, are variables. Why am I not allowed to access the job server directly like my local machine ? Why do I see these variables ? If variables are the only way to set a path, then how do I set the path ?

Thanks.