Administrative expenses are part of the operating expenses (along with selling expenses). Administrative expenses include expenses associated with the general administration of the business. Examples include the salaries and fringe benefits of the company president, human resource personnel, accounting, information technology, the depreciation expense for equipment and space used in administration, as well as supplies, utilities, etc.
Under the accrual basis of accounting, administrative expenses appear on the income statement for the period in which they occurred (not the period in which they were paid).