StartCoroutine("functioncalls", 2f);
StartCoroutine(functioncalls());

void Call()
{
    Invoke("FunctionCall",2f);
}

void FunctionCall()
{
    Debug.Log("this function run");
}

void Call()
{
      StartCoroutine(functioncalls());
}

IEnumerator functioncalls()
{
    yield return new WaitForSeconds(2f);
    Debug.Log("this function run");
}

IEnumerator Countdown(int seconds)
 {
       while (seconds > 0) {
            Debug.Log(seconds);
            seconds--;
            yield return new WaitForSeconds(1f);
       }
       Debug.Log("Go!);
 }

StartCoroutine(Countdown(10));