Looks like it’s got something to do with having geometry at a great distance from the origin and the camera set to Parallel Projection. Set it to Perspective. It would be a good idea to clean up the stray lines and other junk floating around the model. Additionally, you’ve got most of the faces in the model reversed. It would be best to correct the face orientation so white faces are exposed before you continue.
You should also reset the model axes and most likely you will want to move the house up above the ground plane which is the red/green plane when the axes are in their default location. Below, I reset the axes and moved the model closer to the origin but I didn’t move it up above the ground plane. You can see a lot of stray lines.
As @DaveR noted, the cause of the transparent effect you are seeing is that model objects are so far away that the graphics system can’t resolve their distances. When this happens, everything “bleeds” through the objects in front, causing seeming transparency. Usually this happens because the model contents are far from the origin. But in your case it is happening because the camera has somehow gotten moved a vast distance away from the model contents. I don’t know exactly how that happened in this model, but it seems likely you tripped a bug (there is a known one involving leader text annotations, but there are none in this model).
This is one of the perils of parallel projection: zoom is produced by scaling the model contents’ height and width onto the viewport, not by moving the camera nearer or farther from them or vice versa. So the camera can be a vast distance away (or very close) and with appropriate zoom the model will look exactly the same. You have little ability to vary the camera distance in parallel projection. Changing to perspective and then doing zoom-extents causes SketchUp to reset the camera position. Afterward you could change back to parallel, though for working on a 3D model I would strongly recommend sticking to perspective.
The rest of what @DaveR pointed out is also good advice.
Thank you so much for the reply. That is what happened as I carelessly zoomed the model in Parallel Projection and moved the camera a great distance away. I was trying to see all the debris in the scene in order to erase. I will change to perspective view as you suggest.
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