On the inventory page, you can see your products' stock values at each stock location. You can also search for your products using the search bar.
On Hand - is the total number of items in your shelf
(Available + Committed = On Hand)
Available - is the number of items in your shelf that are available for selling or building.
(On Hand - Committed = Available)
Committed - is the number of items in your shelf that are already committed or have been bought but not shipped out yet.
(On Hand - Available = Committed)