The short answer is that SetNameToTime is a program designed to rename digital camera jpg and tiff files. A file renaming program you may think, that is hardly a new concept - so why use this one?
Almost all jpg and tiff files produced by modern digital cameras contain information like the date and time the picture was shot, if a flash was used, the shutter speed, the f-stop and a lot of other information. SetNameToTime can extract this information and use it to rename the file.
The first version of SetNameToTime would use the date and time only to produce a name like 2003-08-11--11-40-00.jpg (year-month-date--hour-minute-second.jpg). The idea was to give each file a unique name and one that would always produce the correct chronological order.
Today SetNameToTime will let you use other data from the file as well. It is up to you to produce the rules for the new file names. You don't even have to use information from the file at all. A name with some text and a counter will do just as well.