What is a drawing that shows you what you would see if you could cut through something and look inside?

A drawing that shows what you would see if you could cut through something and look inside is called a "cross-section." This type of illustration reveals the internal structure and components of an object, such as a building, machine, or biological organism. Cross-sections are often used in architecture, engineering, and Biology to provide a clear understanding of how things are built or how they function internally.