Sprite
A sprite in Rusty Engine is a 2D image, how it is placed on the screen (translation, rotation, scale, and layer), its collider, and other associated metadata. You will use sprites for all the graphics in your game. Many sprites will represent some thing. For example, a race car sprite may represent your player character in your game.
A barrel sprite may represent an obstacle, an enemy, or maybe it's just part of the background. It's up to you to decide how to treat the sprites.