hello. what you are showing is not a plane, it’s a hatch, and that can’t be imported in sketchup. you can convert them to regions, but as I reported in a post it is not importing it nicely. ( Strange way of handling autocad Regions ) You’d better create faces with those hatches boudaries by intersecting or using face creating plugins.
If your profile is correct, I see you are on sketchup 2018, you’d have to check if that version was already able to import autocad regions
(to convert hatch boudaries to regions, use the REGION command in autocad)