This program, utility or function does not have a useful manpage. Please do not report this as a bug, because this has already been reported as a bug; when a manpage becomes available it will be included, and the bug report closed http://www.debian.org/Bugs/ contact the package maintainer in order to avoid several people working on the same manpage.
Try the following options if you want more information.
foo --help, foo -h, foo -?
whatis foo, apropos foo
check directories /usr/share/doc/foo, /usr/lib/foo
dpkg --listfiles foo, dpkg --search foo
find / -name 'foo'
The documentation might be in a package starting with the same name as the package the software belongs to, but ending with -doc or -docs.