Gradle Installation
This is the directory where your Gradle installation is located. If not specified otherwise in the properties of the project, this Gradle installation will be used to load Gradle projects and execute tasks. An additional benefit to set this directory is that if it also contains the sources of Gradle, CTRL clicking on a class of Gradle in a .gradle file will bring you to the sources of the class. Also the editor in NetBeans will see as if this Gradle installation is on the class path of the opened .gradle files.
If you select "Prefer wrapper" and your project has the Gradle wrapper files generated (gradle/wrapper/gradle-wrapper.properties) then the version specified for the Gradle wrapper will be used (unless it is specified otherwise in the project properties). It is recommended to select this option for best compatibility with projects having a Gradle wrapper.
Regardless of the additional options, I recommend to set a local directory of a Gradle installation here, since if you don't, you will lose some editor features of .gradle files. You can always override this in the project properties if you would like so.
This specifies directory where Gradle stores its caches and additional files needed for it to work. Usually you should leave this field blank to use the default but if you do not have enough disk space in the default location, you might adjust it to whatever you like (a bug in Gradle prevents this feature from actually being used for useful purposes).