What's unclear?
It's saying police cannot be hired as bouncers, or as roaming security. They aren't hired as staff, they're hired for presence.
In other words, you can't hire them to replace your own staff for checking ID at the door, etc.
They're there as deterrence for people who would otherwise cause a stir if police weren't there.
Also if you're going to copy/paste in your replies, please make sure you're including the source for context - in this case the information is relevant only to London, Ontario.