See SQL Trace and also dbms_session (for your own session) and dbms_monitor (for others session):
Owner Package Procedure Argument Type In Out D Opts
--------------- ---------------------- ---------------------- ---------------------- -------------------- ------ - ----
SYS DBMS_SESSION SESSION_TRACE_DISABLE U
SESSION_TRACE_ENABLE WAITS PL/SQL BOOLEAN IN Y U
BINDS PL/SQL BOOLEAN IN Y
PLAN_STAT VARCHAR2 IN Y
Options: A: Aggregate, D: Deterministic, F: auth. deFiner, P: Pipelined, U: auth. current User
Owner Package Procedure Argument Type In Out D Opt
--------------- ---------------------- ---------------------- ---------------------- -------------------- ------ - ---
SYS DBMS_MONITOR SESSION_TRACE_DISABLE SESSION_ID BINARY_INTEGER IN Y F
SERIAL_NUM BINARY_INTEGER IN Y
SESSION_TRACE_ENABLE SESSION_ID BINARY_INTEGER IN Y F
SERIAL_NUM BINARY_INTEGER IN Y
WAITS PL/SQL BOOLEAN IN Y
BINDS PL/SQL BOOLEAN IN Y
PLAN_STAT VARCHAR2 IN Y
Options: A: Aggregate, D: Deterministic, F: auth. deFiner, P: Pipelined, U: auth. current User