DDIC objects are data dictionary objects, anything that you can create via SE11, including Tables, Data Elements, Domains, Search Helps, Lock Objects, Views, structures, table types, etc.
The ABAP Dictionary centrally describes and manages all the data definitions used in the system. The ABAP Dictionary is completely integrated in the ABAP Development Workbench. All the other components of the Workbench can actively access the definitions stored in the ABAP Dictionary.
The ABAP Dictionary supports the definition of user-defined types (data elements, structures and table types). You can also define the structure of database objects (tables, indexes and views) in the ABAP Dictionary. These objects can then be automatically created in the database with this definition. The ABAP Dictionary also provides tools for editing screen fields, for example for assigning a field an input help (F4 help).
The most important object types in the ABAP Dictionary are tables, views, types (data elements, structures, table types), domains, search helps and lock objects