* "Actress" is a noun, not a description of the job. It's more natural to say what kind of job it is: "Her job is acting," or "She's an actress."
* The sentence could be interpreted as a statement about the person's literal job title. It sounds like it could mean "She's employed as the person called 'Actress'."
Here are some better ways to say it:
* She's an actress. (This is the simplest and most direct way to say it.)
* Her job is acting.
* She works as an actress.
* She's in the acting profession.