A schema object is a named database item that belongs to a schema, such as a table, view, procedure, function, trigger, package, or stored code unit. In Oracle and other relational systems, schema objects organize data and logic, and they are often the units that permissions are granted on.
Schema objects matter in security because they can also be used to store and run code. If an attacker gains SQL injection into a privileged account, they may create or modify objects to persist access, hide logic inside stored procedures, or compile Java and PL/SQL as part of an execution chain. Defenders monitor schema object creation, changes, and unusual privileges, because a database that can build and execute trusted objects can become an attack platform instead of just a data store.