Is this your model? Or did you download it from somewhere?
If it's your model then you can fix it in your CAD software. What CAD software did you use?
If not, try the mesh tools as nallath suggests or you can use the netfabb repair service (free web service but you have to create an account).
Also you can mess with the standard mesh options in cura. I would try unchecking "union overlapping volumes" or checking "extensive stitching". just toggle them all.
The model is non-manifold. The following plugin can try and fix those issues for you: https://marketplace.ultimaker.com/app/cura/plugins/fieldofview/MeshTools
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