The executor (called a personal representative in some states) is the person named in a will or appointed by a court to wind up the person's financial affairs after death. Basically, that means taking care of property, paying bills and taxes, and seeing to it that assets are transferred to their new rightful owners. If probate court proceedings are required, as they often are, the executor must handle them or hire a lawyer to do it. (For more on probate, see Nolo's Probate FAQ.)
If you have a complicated estate or just need legal advice, Nolo can help you find a lawyer.