The Inventory shows all the items you're carrying in your Bag and Pockets. You can also view any weapons or Items you have equipped. You can also view your current Quests from the scroll icon (top-left), and your Crafting Menu from the tools icon.
The top of the Inventory shows your Parameters - HP, Hunger, Thirst, and Curse. The higher your HP, Hunger, and Thirst meters are the better. However, your Curse Points should be as low as possible.