When it comes to describing a person who occupies a particular position in an organization or company, "fills one position" is commonly used. However, there are a variety of synonyms that can be used to describe this same concept. Some of these synonyms include "holds a role," "is in charge of," "occupies a seat," "has a post," "sits in one's place," "holds a position," "is employed as," "is appointed to," "is assigned to," and "carries out duties as." Each of these phrases can be used to convey the idea of an individual being responsible for a specific job or function within an organization or company.