The Editor Mode allows you to visually navigate and edit your scene in the Unreal Engine Viewport during the editor time. When you click the Play button, the simulation begins.
When the Editor Mode is enabled, ArcGIS Maps SDK for Unreal Engine loads ArcGIS Map content into the Viewport without playing the level. This mode is useful when you place an object in the level for example.
For more information about the Viewport, see Unreal Engine Documentation: Using Editor Viewports.
To enable or disable the Editor Mode:
The Models Panel UI is synchronized with the ArcGIS Map Actor. Click on the Settings tab, and find checkboxes to enable or disable the settings. The Editor Mode option is enabled by default.