A businessperson (also businessman or businesswoman) is someone who works at a job that focuses on making money. Generally, it is someone who works in the management (at any level) of a company. Sometimes the word means an entrepreneur or a merchant.
Many businessmen wear standard business clothes: a suit with collar, shirt, and necktie. However, this depends on the company, the local culture, and the country. In more informal places, neckties need not be worn.
Businesswomen's clothes have gone through many changes. Dresses and suits are common today.