Skype To Go is a service that lets you make cheap phone calls over Skype from a regular phone. Here's how it works. You sign up for a Skype To Go phone number that's linked to your Skype account. You can then dial that number from any phone to initiate a phone call to another phone at the same rates that you would pay if you were using Skype on your computer. In other words, if your mobile carrier charges $.99 per minute to call New Zealand and Skype charges $.02, you can just call a local number and pay the Skype rate.
Skype has been offering this service for a few years, but it was previously part of the Skype Pro plan. Now Skype is making Skype To Go available as a free service for all paying users. OK, I guess that means it's not technically free. But if you already have some credit in your account for making long distance phone calls, you can sign up for a Skype To Go number for no additional cost.