What is the total units on order from Exotic Liquids?
"Exotic Liquids" is the CompanyName; total unit on order = Sum(UnitsOnOrder)
SELECT SUM(T1.UnitsOnOrder) FROM Products AS T1 INNER JOIN Suppliers AS T2 ON T1.SupplierID = T2.SupplierID WHERE T2.CompanyName = 'Exotic Liquids'