iFile and openSSH are to modify file system.
For example you went onto torrent site and got a .deb package of a program that normally cost money in App Store or Cydia. (by let's say typing into google "progname torrent") You can install it using openSSH (think in terms of Command Prompt in Windows or Terminal in Linux). iPad is a Linux distro called Darwin, and openSSH is just a Terminal on it. You need it to mod your iPad in some instances. When you install openSSH, there won't be icon on your iPad, it's a service, into which you can login through terminal.
SHSH, as above confused with openSSH, is related to Mac's hardware encryption. SHSH is a marketing device, it enables exclusivity. Like face control at clubs.