MonoBehaviour.StartCoroutine returns a Coroutine. Instances of this class are only used to reference these coroutines and do not hold any exposed properties or functions.

A coroutine is a function that can suspend its execution (yield) until the given given YieldInstruction finishes.

// - prints "Starting 0.0"
// - prints "WaitAndPrint 5.0"
// - prints "Done 5.0"
print ("Starting " + Time.time);
// Start function WaitAndPrint as a coroutine
yield WaitAndPrint();
print ("Done " + Time.time);
function WaitAndPrint () {
	// suspend execution for 5 seconds
	yield WaitForSeconds (5);
	print ("WaitAndPrint "+ Time.time);
}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    IEnumerator WaitAndPrint() {
        yield return new WaitForSeconds(5);
        print("WaitAndPrint " + Time.time);
    }
    IEnumerator Example() {
        print("Starting " + Time.time);
        yield return WaitAndPrint();
        print("Done " + Time.time);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def WaitAndPrint() as IEnumerator:
		yield WaitForSeconds(5)
		print(('WaitAndPrint ' + Time.time))

	def Example() as IEnumerator:
		print(('Starting ' + Time.time))
		yield WaitAndPrint()
		print(('Done ' + Time.time))