新手照着书写实例，麻烦哪位帮我解释下这什么什么意思

c:\program files (x86)\microsoft visual studio\myprojects\ex05_4\mainfrm.cpp(4) : fatal error C1083: Cannot open precompiled header file: 'Debug/Ex05_4.pch': No such file or directory
Error executing cl.exe.

MainFrm.obj - 1 error(s), 0 warning(s)
错了几个了，点错误行光标显示这里#include "stdafx.h"，在线等啦