This mod is for importing from a PhpWiki dump file. PhpWiki is a wiki engine written in PHP. The first version, by Steve Wainstead, was in December 1999 and was the first Wiki written in PHP to be publicly released. See phpwiki for more details.
See Mods Admin for instructions on how to install a Mod.
However, this mod is currently (July 2007) not well packed under mods.tikiwiki.org, and you need to fetch it from sf.net cvs area:
You need tiki-import_phpwiki.php set in your tiki root directory, and tiki-import_phpwiki.tpl under your templates directory.
Once installed, you will see a new option at "Admin > Import PHPWiki Dump"