The much anticipated Windows Terminal Preview is now available from the Microsoft Store. While it shows great promise, as this is a very early preview, you should expect to see some bugs, crashes, and quirks that will be fixed in future builds. Microsoft briefly made the preview available earlier yesterday, but they were just gearing up for its release and it was not ready. The working version of Windows Terminal is based on version 0.2.1715.0.0. To get the preview you need to make sure you are running Windows 10 version 1903 and on build 18362.0 or higher.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-terminal-is-here-in-its-multi-tabbed-console-glory/