Basically, its going to the location/set and assessing any risks that may occur to the crew.
That is a big 'may' and really, I think it sucks because if you have multiple of sets/locations and you're expected to do a risk assessment then that's a lot of man hour wasted.
It's not insurance (although you are required to be insured) and have a public liability insurance and on top of that, there is this risk assessment!
I'm sure there is a reason to why it is required but it sucks
Perhaps you can find a student who does Safety&Security, who will do that for you just for experience. Risk-assesments a one of the basics in that area, and can best be learned by just making/doing them for real.