WiFi is absolutely essential for any tablet, as at some point it will need to connect to the internet. This may be for registration, updates, or interacting over the internet, as well as downloading content and watching streaming films and television programmes. WiFi is a wireless communication method, just like Bluetooth.
The Dragon Touch K8 Kids naturally comes with WiFi. Although this will be needed at some points, constant internet connection is not essential. A tablet will be able to function away from an internet connection, using content that is installed on the tablet, like some apps and games. However, functionality does diminish away from an internet connection. Should WiFi not be used for any reason, it can be a good idea to turn it off in order to preserve battery life. It is often the case that, if WiFi is not available, that power sources to recharge the battery are also limited, so battery drain should be reduced.