Rigidbody.velocity is rotating instead of moving my character?

I'm using a tutorial here: https://unity3d.com/earn/tutorials/projects/space-shooter/moving-the-player and here's my code

 public float speed;

 private Rigidbody rb;

 void Start()
 {
     rb = GetComponent<Rigidbody>();
 }

 void FixedUpdate()
 {
     float moveHorizontal = Input.GetAxis("Horizontal");
     float moveVertical = Input.GetAxis("Vertical");

     Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
     rb.velocity = movement;
     
 }

It's rotating the character I imported instead of moving it horizontally and vertically. What am I doing wrong?