This plugin, usable only with a block theme like Twenty Twenty-Two, adds the legacy widgets block in the Site Editor (FSE).
With the legacy widgets block, you can use the legacy widgets as Navigation Menu for example.
This is why this plugin reintroduces the WordPress legacy Menus screen to be able to manage menus you want to use with the Navigation Menu widget.
This also allows to use external plugins legacy widgets which might not have already been converted to blocks.