The letter J is pronounced as H in the English word HOT in some countries or some regions of some countries. Other regions and countries pronounce it in a much more intense way, similar to the sound you can hear in Arabic or in Hebrew. If you can't understand how the strong way is pronounced, pronounce it like the H in HOT and you will be on the safe side. The J is always pronounced with this sound (or the strong one I've mentioned. As for the G, when followed by I or E it's pronounced the same way, while if followed by any other letter it's pronounced as the G in GHOST.