Hi Kiran
UJFS is basically a tcode for BPC consultant. If you are new to BI, I am sure you are unaware of BPC as well.
If you let us know what do you exactly need in BI, we could assist you further on whether you need UJFS or some other tcode.
BTW, UJFS is used to give you information about the files in BPC server. File include transformation files, conversion files, data input files and many more based on the environment and models.
Hope this helps
Regards
Karthik