Thought I’d throw in my 2 cents.
Anyone interested in flight simming most probably was interested in aviation for a while before that. In extension, that should mean that the person has either formally studied aviation or reads about it as a hobby so he should at least have a grasp of the fundamentals and knowledge of the basic instruments and systems used in most aircraft.
I personally had a great time when I first started learning BMS. I already had a couple years of aviation knowledge under my belt just as a hobby (I’ve applied to our air force before but because of a speech impediment I sadly can’t be accepted no matter my qualifications) and the BMS manuals were comprehensive and answered most if not all of the questions I had in mind. Any acronyms I didn’t understand I was able to know through a quick Google search, using acronymfinder.com, or just asking the forums here.
It also helps to have a passion for this kind of stuff because the information available is massive and really does require a certain degree of dedication to become an adequate driver. If you’re coming in to a flight sim expecting everything to be laid out in and exact step-by-step format you’re gonna have a really hard time. This sim is arguably the most realistic commercially available sim and it didn’t reach that level by being easy.
Not sure where I’m going with this, but if you have the dedication and passion for this sort of thing you’ll be able to understand everything by putting in some extra effort and actively searching for answers yourself either in the manuals, here in the forums, YouTube, or elsewhere on the internet.