The sdk-style projects have a few automatic includes.
By default, the sdk has something like <None Include="**/*"> (simplified) that is added (included) before your project’s contents. But you don’t want your file to be in the “None” set, but in the “EmbeddedResource” set.
MSBuild doesn’t have any problem with the files being in more than one item group, but it should only be in one so IDEs don’t get confused (and display the file only once an show the correct build action).
So the two statements mean “remove it from the None set (items) and add it to the EmbeddedResource set (items)”.