What is meant by 4 GL?

Question

I came across the term 4GL(generation language) in reading about Oracle ADF Busniess components . I want to know what exactly is 4GL ?

This is the actual quote from the book Oracle Fusion Guide:

Oracle ADF Business Components is the business services layer of choice in Oracle Fusion application development. Compared to other persistence layers, ADF Business Components provides exceptional built-in business application functionality and maximally declarative experience that makes it a perfect match for those who seek an end-to-end fourth generation language (4GL) Java EE development architecture.