、。
She was very popular when she was young.
Literal
She [topic-は] young time, very popularity [subject-が] existed.
人気がある (to be popular, literally 'popularity exists') uses がある to express having popularity as a quality. The past とても人気があった means she had a lot of popularity. 人気 (にんき) is the standard word for popularity with people — used for celebrities, products, restaurants, anything that draws public favor.