Many (probably most) documentation pages have a SEE ALSO section which provides links to related documentation. The first "Perl module: ..." link I provided above ("perlmod Perl modules: how they work") has a link to perlootut - Object-Oriented Programming in Perl Tutorial. (It sounds like a tutorial is what you need.) Within that documentation, you'll find the answer to your question:

"Inheritance lets you create a specialized version of an existing class. Inheritance lets the new class reuse the methods and attributes of another class. ..."