What is Without this twisted blade some planes could not fly and ships could not move?

The phrase refers to the concept of a "propeller" or "rotor," which is essential for the propulsion of aircraft and certain types of ships. Without these twisted blades, planes would be unable to generate the lift needed to take off, and ships reliant on propellers for movement would be unable to navigate. Thus, these twisted blades are crucial for the functionality of various modes of transportation.