If it’s not just a copy & paste mistake when posting it here, make sure the sing UnityEngine; is actually using UnityEngine;
You also miss the closing bracket right at the end which closes the class.
Also make sure your filename is the same as your class name. I don’t think you want the name NewBehaviourScript.
format and indent your script properly so you can actually read it and it’s much easier to spot errors.
Remove any functions (and comments) you don’t need / use.
I have also a parsing error myself when reading your question title…
So your script should look like this:
//C#
//Filename : NewBehaviourScript.cs
using UnityEngine;
using System.Collections;
public class NewBehaviourScript : MonoBehaviour
{
void OnMouseEnter()
{
renderer.material.color = Color.cyan;
}
void OnMouseExit()
{
renderer.material.color = Color.white;
}
}
Once more: You should use an actual meaningful name for the script / class. Something like “MouseOverHighlight” or what ever you want as long as describes the purpose of the script.