Can anyone clearly explain to me what does this mean please??

Cannot open scene at path Assets/Scenes/SampleScene.unity. Maybe the scene hasn’t been imported. This can be done with an AssetDatabase.Refresh() call.
,Cannot open scene at path Assets/Scenes/SampleScene.unity. Maybe the scene hasn’t been imported. This can be done with an AssetDatabase.Refresh() call.

There is a scene file in Assets/Scenes called SampleScene that seems corrupted or something. Maybe that scene contains prefabs or somethign you do not have in your project folder.

If that scene is not important to you, delete the scene file and continue your life :smiley:

If the scene is important, try to do this process to refresh all assets: