Understand the logic of layers and masks; Organize objects based on the logic of layers and masks.

[RaniB29]

https://docs.godotengine.org/en/stable/getting_started/first_3d_game/06.jump_and_squash.html

Layers and masks organized as: 1 - player 2 - enemies 3 - world 4 - objects (letters and DeliveryPost)