NEVER click on the links in an email like this.
It will almost certainly take you to a "fake" web site make to look like the real Apple web site.
If you then logon to that fake web site the criminals will steal your userid and password.
Go into the GENUINE Apple web site and change your password.
Note that criminals send out thousands of emails like this hoping to catch people out. Many people who get it wont even have an Apple account.
If you DO have an Apple account then just go into your PROPER Apple account and change your password.