PL/SQL is an extension of Structured Query Language (SQL) that is used in Oracle. Unlike SQL, PL/SQL allows the programmer to write code in a procedural format. Full form of PL/SQL is "Procedural Language extensions to SQL".
It combines the data manipulation power of SQL with the processing power of procedural language to create super powerful SQL queries.
PL/SQL means instructing the compiler 'what to do' through SQL and 'how to do' through its procedural way.