A MappedinVenue is a specific place (like a mall) with one or more Maps (typically representing different floors) and Locations (stores, washrooms, elevators, etc).
A Venue can have more properties such as 'name' and 'slug'. The Mappedin 'things' object is where you would specify what properties you want to download for Venues. Only specify what you will actually use, to minmimze transfer time. Work with your Mappedin developer relations contact to set up any custom properties you need.
See below for an example a 'things' object with available Venue properties specified:
venue: ['slug', 'name', 'language', 'address', 'city', 'state', 'postal', 'telephone', 'latitude', 'longitude', 'website', 'operationHours'],