What is standard (or traditional) auditing?

From the Oracle Documentation:

"In standard auditing, you enable auditing of SQL statements, privileges, schema objects, and network or multitier activities. You can audit a specific schema table if you want."

You need to set AUDIT_TRAILto "DB" or "DB,EXTENDED", in order to start using standard auditing.
After this is done, you may execute the AUDIT statement to start auditing of different actions according to your need.
You can choose to write the audit-trail to the database itself, or to operating system files.

Oracle Database audits all data manipulation language (DML) operations, such as INSERT, UPDATE, MERGE, and DELETE on the SYS.AUD$ and SYS.FGA_LOG$ tables by non-SYS users. (It performs this audit even if you have not set audit options for the AUD$ and FGA_LOGS$ tables.)

Typically, non-SYS users do not have access to these tables, except if they have been explicitly granted access. If a non-SYS user tampers with the data in the SYS.FGA_LOG$ and SYS.AUD$ tables, then Oracle Database writes an audit record for each action.

To view the standard audit trail, query the views DBA_AUDIT_TRAIL and DBA_COMMON_AUDIT_TRAIL.

Source: Oracle 11g Documentation


Note that in later releases, Oracle is often refering to standard auditing as "Traditional Auditing", since Oracle 12c introduced the concept of Unfied Auditing.