When you have people on the job for years who speak the language, yes, it is assumed that they are aware of certain safety issues and such like.
When you give people a chance and hire someone who doesn't speak the language, it's considered helpful if you try and educate them to the perils and or issues of the work place.
Sounds like the definition of an "Employee Handbook" to me.
Which should read exactly the same in English or Spanish.