Error on simple code cs0119

Getting an error message in reference to the transform.position variables. Any ideas?

 public class Respawn : MonoBehaviour {
 
     public float deathvelocity;
 
     void Update () {
         if(rigidbody.velocity.y > deathvelocity){
             transform.position = Vector3(-5,0.5,-5);
         }
 
     }
 }