These are empty advent calendar boxes from 2010, 2012, 2014, and 2016. There are no Lego pieces inside the boxes but they still have the inner compartment trays. The boxes could be re-used this Christmastime since the doors are still intact, or they could be used to store pieces in the small compartments.
There's another advent calendar from 2009 (set #7687) that you're welcome to have but it's missing two of the 24 doors.