How did vertebrae prevent from grinding against one another?

The intervertebral discs, which are between vertebrae, are the parts that prevent the vertebrae from grinding against one another.

The intervertebrals discs act as a cushion; they absorb the stress and shockw that occur during movement, preventing such grinding.

Inter-vertebral discs separate vertebrae from one another. They are cushion-like discs which absorb the shock the body experience during movement and prevent the vertebrae from grinding against one another.