A detailed description is as follows;

A procedural language created especially for the Oracle Database administration system is called PL/SQL. The client transmits SQL statements to the server, which processes them and returns the results. This is the foundation of the client/server model used in the PL/SQL execution architecture.

Prior to being performed, a PL/SQL block is parsed to look for syntax errors. The block is converted into p-code, an intermediate format, if the block is error-free. The shared pool in the server's memory is then loaded with this p-code, allowing numerous users to reuse it.

The server gets the p-code from the shared pool and runs it when a user performs a PL/SQL block. The server controls the execution of various programs in the background to manage the execution of PL/SQL code. 

The PL/SQL architecture has 2 major parts - PL/SQL engine as well as the SQL statement executor. The PL/SQL engine is responsible for executing the PL/SQL code and the SQL statement executor runs SQL statements. On execution of a PL/SQL code, the PL/SQL engine retrieves the compiled code. An SQL engine executes the SQL statements outside the PL/SQL blocks.