The phrase "addition to acting" means something that a person does in addition to their work as an actor. It refers to other activities or responsibilities that they have in their life or career alongside acting. Full definition
In addition to acting in a supervisory capacity, they often engage in decision - making, purchasing, merchandising and accounting duties. (jobhero.com)
In addition to acting as counsel, he has served as an arbitrator in international commercial disputes. (bryancave.com)
In addition to her acting career, she has directed, written, and starred in a number of shorts and web series. (rottentomatoes.com)