a handwritten or printed work consisting of pages glued or sewn together along one side and bound in covers.
As a noun, the movement of this sign is formally twice. However, the movement may be once in effect of phonological co-articulation even if it's noun in sentence.
Plural noun: books in a pile; a stack of books.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.