Perl is a programming language suitable for writing simple scripts as well as complex applications — see https://www.perl.org.
Strawberry Perl is a perl environment for MS Windows containing all you need to run and develop perl applications. It is designed to be as close as possible to perl environment on UNIX systems.
It includes perl binaries, compiler (gcc) + related tools, all the external libraries (crypto, math, graphics, xml…), all the bundled database clients and all you expect from Strawberry Perl.