Intro or what are Kexi objects?
Kexi objects are the top-level entities of type Table, Query, Form, Report, Script or Macro. They are compared to perhaps separate document types except of course they are not physical files (in Kexi nothing touches physical files except the database that handles the actual storage but this is rather an implementation detail).
The latter two objects aren't in official use: Script is experimental and subject to rework; Macros (MS Access style, see old dev docs) are only planned.
If you're new RAD world, for info on what these types of objects are, google for MS Access objects. Many of its concepts and naming make sense with the exception of Modules -- Kexi tends to use Scripts term instead.