If you’ve used the SOLIDWORKS Section View tool and noticed that your model appears hollow, similar to a surface body, this has to do with the Section Cap options.
This is because you may have inadvertently deselected the option “Show Section Cap” in the Section View PropertyManager. With this deselected, the cut “surface” is not shown so you can see inside your model.
Enabling the option will show the cut face so the model appears solid:
You also have an option to show the Cap Colours to differentiate the cut faces. Select the option “Keep cap color”.