It means anyone with Internet can email you anywhere in the world - that is a good thing (it may not be that useful if you have a business in Saint Louis, unless one exports)
But besides email it means anyone with an Internet connection can check your machine out using free scanners (nmap.org)
If you think about it for a minute, all hackers in the world are looking for mischief, that means that as more and more people go online there will be more criminals that go online. More people with free scanners checking into your machines.
So more scanners, more hackers, more devices attacking.
The good thing of global Internet is that someone in Europe with money could buy your stuff (if one is set up for it)
remember that the PCI DSS 3.0 standard has been updated (as of November 2013)
Specifically this part:
Notice how after 6/30/2015 Penetration testing quarterly is not "recommended", now it is required.
contact us to review your security profile