I'm not sure what it does, but it doesn't seem to be that important.
If I shut it off, the Internet runs faster and better.  If I leave it on, I send a lot of information that I can't see leave my computer.
What I do know:  It is part of the Windoze system.  It does not return a value of any kind to the screen when I run it, even from the cmd line.  It can run multiple incidences.
I speculate that is one of Micro$loth's Better Ideas that tries to compete with Unix/Linux, the prefix 'ls' tied to 'host' implies that it would list hosts.
I'd like to find out what it really does.
Kevin the Chaos Vampire