Can I use verizon Iphone 5 in my country?

Hi, in my country iphone 5s are too expensive, over $1400 so i'm planning to buy one from ebay. Verizon phones there are very cheap ($600) but only GPS operators are in my country. I have heard that verizon has put sim card slot into its Iphone 5s so anyone who is abroad can use that phone with wanted GPS operator. Is it true, if so will i have to unlock my iphone 5 to make it work?
PS: What does bad ESN mean and will i be able to still use phone?

Yes, if the iPhone by Verizon you purchase has been unlocked already, you will be able to use it with all GSM carriers outside the US. If it isn't unlocked yet, you can simply do that yourself by getting a factory unlock from one of the big online unlock services like http://www.cellfservices.com/

A bad ESN means that the serial number of the device has been blacklisted/barred by Verizon, so you won't be able to use it, not even if unlocked, so stay away from those devices.