This is the 488th most frequent Russian word.
подготовки
"Preparation"
Here, "подготовки" is a genitive case form of the noun "подготовка" used to describe the process of preparation for a project.
В процессе подготовки проекта было много изменений.
During the project preparation process, there were many changes.
In this example, "подготовки" signifies the level or state of being prepared, again in the genitive case to modify "уровень" (level).
Её уровень подготовки к соревнованию удивил всех.
Her level of preparation for the competition surprised everyone.
In this sentence, "подготовки" is used as a noun in the genitive case related to the purpose of the book, indicating 'preparation for exams'.