Info is a type of documentation. The documents are in a file format called texinfo, and can be read on the command line with the info program.
The Info KIO worker allows you to read the info pages installed on your system, from within Konqueror. You can use it very easily:
This would show you the top level node of the Info documentation for the gcc compiler.
Info is a GNU replacement for man, but is not widely used outside of GNU software.
You can quite easily browse the info documentation you have installed from within the KHelpCenter application, or you can use the info KIO worker directly from within both Konqueror and the mini-cli.