It means a programming language that is better designed and works better than most of today's programming languages, to start. Think better than C and Golang, simpler than Python.
It also means a compiler. A language with better toolchain and better development experience.
It doesn't mean an IDE, at this stage. An IDE might be as much work as the language. Although integrating with an IDE can improve the debugging experience.
What would your dream programming language look like?
Cost to experiment being low doesn't make non-obvious ideas obvious. As a trained researcher with patents I'm no longer surprised by how often simple ideas have remained undiscovered for decades.