It defines a DSL for your build that looks roughly like Scala code. But… it’s not! And there is a confusing “resolution” system for build tasks/settings. It’s also slow as shit. See https://www.lihaoyi.com/post/SowhatswrongwithSBT.html for a comprehensive takedown. If you’re interested in just playing around with scala I would use

https://scala-cli.virtuslab.org

Or for larger projects, the thing the author of the linked article is plugging (mill).