prj to tif conversion can actually represent many things, but typically it's used for export of various project files (often have .prj extension) to TIFF graphics. Projects are typically tied to the original software, so you will have to use that particular software if you hope to export the project.
Overall it's very hard to give a specific answer for this, because dozens of different .prj files exists, so unless you know the origin of your file it will be pretty much impossible to give exact answer.