Question on fsck -N

[Wen Guangcheng]

Hello Gurus,

After a earthquake I wonder whether I should  check a server's file system.
Someone suggests me to use "fsck -N device name". If  it shows some errors
then the file system should be check and repaired. 
But from man page of  fsck the explanation of -N option is as follows, 
-N     Don't execute, just show what would be done.

I am not sure what it means. Would anyone give me more explanation of 
-N option?   Thanks in advance.

Best regards,

--Wen