What is fashion marketing & management? what does a person in that field doooo?

I think you may mean Fashion Marketing & Merchandising.

Here's the nickle version of a reply:

Fashion MARKETING is the practice of advertising fashion (clothing, jewelry, leather goods, accessories, etc.) to select audiences.

Fashion MERCHANDISING is the practice of identifying and/or producing select products for a particular customer base.

For example, in the jewelry business, MERCHANDISERS determine which products they want to purchase from vendors and manufacturers and how much they want to sell them for. Then, it is up to the MARKETING department to determine how to present those products in front of the right buying audience.

This is a very simplified answer to your query. I hope it helps you.