Spawns a prefab at a random position.

SpawnPrefab.cs

// Assign the prefab in the editor
public GameObject prefab;

void Update() 
  {
    // Define range for random values
    int spawnPointX = Random.Range(-2, 2);
    int spawnPointY = Random.Range(-2, 2);
    int spawnPointZ = Random.Range(-2, 2);
    Vector3 spawnPosition = new Vector3(spawnPointX, spawnPointY, spawnPointZ);

    // Spawns a prefab at a random position when a key is pressed
    if (Input.GetKeyDown("space"))
    {
      Instantiate(prefab, spawnPosition, Quaternion.identity);
    }
  }