Pick up most any reference book about PL/SQL and you'll read that it is Oracle's "procedural extension to Structured Query Language (SQL)." If that definition doesn't help much, consider what it assumes you know:
What a computer "language" is
What "procedural" means in this context
Some concept of Structured Query Language, including the notion that SQL is not procedural
The idea of a language "extension"
Let's look at each concept in turn.
A computer language is a particular way of giving instructions to (that is, programming) a computer. Computer languages tend to have a small vocabulary compared to regular human language. In addition, the way you can use the language vocabulary—that is, the grammar—is much less flexible than human language. These limitations occur because computers take everything literally; they have no way of reading between the lines and assuming what you intended.
Procedural refers to a series of ordered steps that the computer should follow to produce a result. This type of language also includes data structures that hold information that can be used multiple times. The individual statements could be expressed as a flow chart (although flow charts are out of fashion these days). Programs written in such a language use its sequential, conditional, and iterative constructs to express algorithms. So this part of the PL/SQL's definition is just saying that it is in the same family of languages as BASIC, COBOL, FORTRAN, Pascal, and C. For ...