If you are using a tool like SQL Developer, you can obtain a good deal of information about database objects, their contents and their status. In SQL Developer the connections pane contains a tree with each object type available to the user. In the image below, the procedures node is expanded and several stored procedures are visible. One procedure has a red circle with an X, indicating that it is invalid. An invalid object has a compilation error and cannot be run.
Right click on an object to view, edit, compile, run, change security access, drop, format or export the object. Error and diagnostic messages are displayed in separate areas along with text written using DBMS_OUTPUT. See the SQL Developer Help documentation for more information. Other third party tools contain similar options as well, but all of the items displayed are based upon the objects and functionality of the Oracle database itself.