Elementary OS is a Linux based operating system that takes a simple and modern design approach. Their headline is "A fast and open replacement for Windows and macOS", with some characteristics closely resembling parts of both Windows and macOS. The newest and upcoming update to Elementary OS will be deviating from its typical upgrade version bump. The most recent release was version Loki (0.4), with previous versions following the format (0.1, 0.2, etc). Elementary OS has decided that with this update the version would not follow suit as 0.5, but instead, "5.0". They felt that due to the stability and adoption of Elementary OS, it should be bumped to a full version; but rather than go directly to 1.0, it was decided that as a "fifth release" the version go directly to 5.0.
Release and information
Currently, there is no set release date for Elementary OS Juno, because the Elementary OS development follows a "release when ready" process. Because it will be based on Ubuntu 18.04 LTS, we know that Juno will not arrive prior to Ubuntu 18.04 LTS (which is set to release in mid-April)
They explain in an official blog post why they don't share many details before a release:
We generally avoid publicly committing to release dates and exact feature sets. This is in part due to past disappointments when we didn't quite deliver something when we initially thought we could, but also to afford us — a completely open source organization — a bit of surprise and showmanship.
As with each full update, substantial improvements and polishing are to be expected. We don't have a ton of details at this time on the specifics of the changes, but we do know that it will offer modern third-party compatibility as it will be running the latest Ubuntu version.