There will be no cell service anywhere outside US. You will have the same service on wifi, as you do at home. Meaning, you can call/text the US/Canada, but not local numbers. There will be no usable emergency calling while there. (If you made an emergency call it would be routed over wifi to a US dispatch center based on your e911 address).
I recommend that once there you put your phone in airplane mode and then manually turn wifi back on. This will keep your phone from searching for a cell signal it will never find (and very rapidly draining your battery), but still allow you to use the only capabilities that will work there.
Since you have the G6, you can also obtain a local SIM card, and place it in your phone for use while abroad. There is some great information here: International Travel with a Republic Phone