What does the 3G mean is it included in an iPad 2 16gb?

The "3G" in the context of devices like the ipad refers to the third generation of mobile telecommunications technology, allowing for cellular data connectivity. The ipad 2 is available in both Wi-Fi only and Wi-Fi + 3G models. If you're looking at an ipad 2 16GB model, you would need to check if it specifies "Wi-Fi + 3G" to confirm it includes 3G capabilities.