I am very new to MIT App Inventor/mobile app development and am working on a project that involves building a mobile app that can pull in location data from a database or spreadsheet and then display the data on a map with location markers. For example, I have a database that contains location data for various client assets and want to be able to visualize that information on a map that displays markers pointing to the geographic location of the assets. Is this possible and where do I even begin with this sort of thing?
Welcome Jonathan.
Here is a tutorial that does most of what you want. It takes the data from a csv file. Get the data from your database and convert it to a csv and this example may work fine for you. 
There are similar examples discussed in the community of this is not exactly what you are looking for.
Regards,
Steve