Congratulation on your new controller. It sounds like she is asking a lot of relevant questions.
It is impossible to give a good professional answer to your question without knowing how you are your business is using Business Central.
Some companies put a lot of effort into having the accurate item cost in the system at all times, some put less or none effort into that.
Some companies have routines in place so that their financial reporting is up to date every day but others only makes sure their financial reporting is up to date by the end of every month or every quarter.
In general you can do your reporting based on item transactions or financial transaction, and in an ideal world those two views of your data should match.
One report you can use is the inventory - sales statistics for the item transaction part of things.
For the financial part of things you can start by analyzing your trial balance or look at the different financial report layouts available under the account schedules.
In some cases it is necessary to customize reports to give you figures you can relate to and trust.
But again it is crucial to know how the system is used and how your accounting is organized in order to understand what data the different reports really are presenting.
