please let me know what this icon mean

what does this icon on the left of the “stem final copy” . I thought they are mesh but I can not run boolean on it. I imported this object from sketch up and mesh lab in dae file, and obj file, and turned into non mesh? I did have one file (dae) successfully imported, and have the triangle mesh icon (I assume?). Any help will be appreciated!!

It’s an empty object that has a mesh parented to it. Empty object is just a helper object, usually for transformations.