How to make an object move with a script which isn't attached to it?

Hello!

I am trying to make a script spawn a prefab whenever the player presses space, facing the direction of the player. The object will then move in the direction of where the player was facing, at a speed of 10. This is the only working code I can figure out, every time I try making the object, which is not what the script is attached to, move, I get an error.

If anyone could show me what could work and why I would be extremely grateful! Thanks!

if (Input.GetKey(KeyCode.Space)) { Instantiate(LasarBeam, transform.position, transform.rotation);

     }