a sentense about set -k .. ?

[alex xmb ratchev]

       If the -k option is set (see the set builtin command below), then all
       parameter assignments are placed in the environment for a command,
not
       just those that precede the command name.


              -k      All arguments in the form of assignment statements are
                      placed in the environment for a command, not just
those
                      that precede the command name.

its not echo $yo yo=7
nor yo=7 echo $yo

in other words , i get not what it does ..
so i ask for a sentense , two .. about it

greets .. axr