Traditionally, the building was all about packaging and compiling the source code. But now the work of a builder is more than that. They have to perform test run, merge code resources with multiple sources, provide documentation, manage dependencies and publish applications.
Thus, the builder became software where you can release apps and change tests. And with Gradle, you can perform all these functions in a single place.
For instance, Gradle is the build tool for Android Studio. It makes Gradle more efficient than other tools. In fact, the whole process of building an Android app is now with Gradle tool. It can work with multiple platforms and has a powerful and compact build language Groovy.