Your smart watch provides some useful information in Green Hell. It displays your food requirements, coordinates and displays a compass. When doing the initial tutorial, you are given a brief introduction to your smart watch.
To open the watch, you need to hold down F. Hold it down for as long as you want to see the watch. You will see a screen similar to the image below. The bars represent Carbohydrates, Fats, Proteins and Hydration. You need to keep these bars filled at all times.
Using the scroll wheel, you can navigate through different screens on the watch. The next screen over will open a compass, where you can see which was is North, East, South & West. Whilst there appears to be coordinates in the middle.
Whilst you can switch through the watch screen one more time to show the time and date. It’s likely that the developers will add more features to the watch in future updates, as Green Hell is still in early access.