Chapter 8 was tough for me When determining the lumber needs

Chapter 8 was tough for me. When determining the lumber needs of the West Street Video. Am I correct to think that the lumber needed is the roof-framing plan?

Lumber is basically timber that is the type of wood which is processed and used in making various structure such as beam, roof, plank etc

Yes lumber needed roof framing plan in order to provide appropriate support to the roof . it also decide the shape and size of the roof.