Dashboard is a longtime macOS feature, first introduced in OS X 10.4 Tiger back in 2005. The feature includes things like sticky notes, a calculator, a clock, a weather interface and other useful widgets.
Since macOS 10.10 Yosemite, Dashboard was disabled by default and could be found only if you search for it. You can still enable it via Mission Control or add it to the Dock, if you’re running OS Mojave or older.
The last time Dashboard was updated was way back in 2011, and while it is available in various forms, its UI or widget designs haven’t been changed since.
Seeing that the feature is being removed entirely in macOS Catalina, it’s very likely that it was not used by a significant number of users.
Should you need any of the widgets that were in the Dashboard, you can find may of them available as part of the macOS Notification Center (upper right corner of the screen), or through a hotkey/trackpad gesture on Apple notebooks.
For quick access to Dashboard, go to the Search bar and type in ‘Dashboard’. After that, hit the Enter button.