Questions & Answers about Она сама готовится к экзамену.
Она готовится к экзамену = She is preparing for the exam (neutral statement).
Она сама готовится к экзамену adds emphasis on she herself. Typical nuances:
- She is doing it without help (no tutor, no parents, etc.).
- She, not someone else, is the one preparing.
So сама here is an emphatic “herself”, not necessary for grammar but important for nuance.