What does Christine’s personal shopper mean?

"Personal Shopper" is a drama film directed by Olivier Assayas, starring Kristen Stewart, Sigrid Povass, Anders Danielson. Starring Li and others. The film was released in Belgium on October 19, 2016.

It mainly tells the supernatural story of Maureen, an American girl in Paris, who was involved in a murder case in Paris as a celebrity's personal fashion buyer.

Plot summary:

Maureen, a young American girl in Paris, works as a caretaker for a famous lady's wardrobe. She hated the job but couldn't find anything better to cover her expenses in Paris. She waited, waiting for news about her twin brother who had recently disappeared. And her phone suddenly began to receive some strange anonymous messages.