What does this mean?

That you are in the wrong forum. :wink:
You use ForgeGradle 3 with a Gradle version it is not compatible with and that’s what it is telling you.
Either use an older Gradle version, or a newer ForgeGradle version.

And please, don’t make screenshots of text messages, but copy & paste the text. Especially such ultra wide one line screenshot which is especially hard to ppl at, especially on mobile. :wink: