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.
Businessmen generally 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 wikt:informalinformal places, neckties need not be worn.
Businesswomen's clothes have gone through many changes. Dresses and suits are common today.