Bevy does not yet have an official editor or other such tools. An official editor is planned as a long-term future goal. In the meantime, here are some community-made tools to help you.
bevy_inspector_egui gives you a simple
editor-like property inspector window in-game. It lets you modify the values of
your components and resources in real-time as the game is running.
bevy_editor_pls is an editor-like interface that
you can embed into your game. It has even more features, like switching app
states, fly camera, performance diagnostics, and inspector panels.
space_editor is another such editor that can be
embedded into your game. It seems to be designed for a Unity-inspired prefab
You can also use Blender as a level/scene editor, by exporting your scenes to GLTF. The Blender Bevy Components Workflow project improves on this experience, by allowing you to setup your Bevy ECS Components in Blender, include them in the exported GLTF, and use them in Bevy.