Normally, a Receptionist is a person whose role is to meet and greet customers, clients, etc. in a place of business. In some offices, such as a law firm you will given a variety of duties or tasks and these can change at times based on the needs of the firm.
For instance a receptionist's responsibilities may include: answering the telephone, sorting and delivering mail to others, typing letters, running errands such as delivering documents to a court house or elsewhere are examples of duties attached to this position.
Usually, a written job description will be provided to anyone applying for this and similar positions. Someone applying for this type position, would usually be friendly, out-going, hospitable, caring, respectful, honest, and discreet as they deal with bosses, callers, visitors and fellow employees.