The Object Selection element allows selection of Business Object.
You can filter by one or multiple properties.
For example if you want to achieve a hierarchy: Country => City => Factory you can add 3 Object Selection elements, the 2 nd (City) element should have a filter for Country and the 3 rd element (Factory) should have a filter for City
You can also click on the "Add related business object selection" button which will automatically add another element and prefill the filters
There are 6 types of conditions - Equals, Not equals, Property equals, Property not equals, Property contains, Property does not contain