In regard to her testimony about what happened in the SUV it is hearsay as no person directly involved told her.
It was hearsay because she didn't see what happened or hear what anyone said. But she was told about it by Bobby Engel, who was in the car. She was under oath, so perjuring herself wouldn't have been a good idea, but there's no reason she couldn't have related what someone told her about what he'd just witnessed.
In addition, hearsay is sometimes admissible at trial. See:
Cassidy Hutchinson’s Testimony Changed Our Minds About Indicting Donald Trump
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