Yes, I think that “value of new orders” is a way of measuring and expressing that new orders have increased in number or scale, i.e. there is an increased demand on production, which will immediately increase unfilled orders and decrease inventory.
Wikipedia (article “Economic Indicator”) expresses it a little bit more clearly than in the book:
Manufacturers’ new orders for consumer goods/materials — This component is considered a leading indicator because increases in new orders for consumer goods and materials usually mean positive changes in actual production. The new orders decrease inventory and contribute to unfilled orders, a precursor to future revenue.