It's just the Dewey Decimal System, so you could look up whatever topic you like to find what it would be classified under. There's thousands of topics that are covered here - there's a reason it's used for every non-fiction clarification in a library - that would be far too numerous to list on a single shelf listing. This library has chosen to prioritize the awkward questions as a way to help someone who otherwise may not know how to get help.

Alternatively, most libraries have a catalogue you can search by keyword and it will give you book results which will let you know where they are on the shelves. But again, that requires you to know that the catalogue exists and how to use it. It's always going to be easier to ask a librarian, who can make sure you find something to help.