When you bend something, like a stick or a piece of rubber, it resists being bent because it has something called "flexural modulus". This is like the stick or rubber's strength in bending. The higher the flexural modulus, the stronger the stick or rubber is when it's being bent.
Think of it like a superhero's power. Some superheroes are really strong and can lift heavy things. Other superheroes are really fast and can run really quickly. Flexural modulus is like a superhero power for things that bend, like sticks and rubber. The higher the flexural modulus, the stronger that thing is when it's being bent.