An Oracle database consists of objects like tables, views, and programs owned by user accounts. SQL is used to perform operations on database objects like creating, modifying, viewing, and deleting them. There are two main types of SQL commands: DDL for defining objects and DML for manipulating data. Users have privileges like creating tables or inserting data that are assigned by the database administrator. Database objects must follow naming conventions and can be created and modified using SQL commands in tools like SQL*Plus.