Happy to help!
Basically what I mean with the see through effect is that when the player character goes behind/under some terrain, you cannot see them. This can be awkward if you're fighting enemies as you can't see whether they are about to hit you/where to shoot. To fix this problem, it would be good if when moving behind the terrain, the terrain itself would become partially transparent, allowing you to see whats happening behind it.
Sorry if I haven't explained it very well. Its a common QoL feature in most 3D games.