Just a few things I quickly found on the internet.

A business developer works to grow a company's profits through attracting new customers and by increasing the spend of existing customers.

A business developer's main area of focus will be to generate new leads with the aim of creating more sales.

Business Development manager skill and qualifications: closing skills, motivation for sales, prospecting skills, sales planning, selling to customer needs, territory management, market knowlege, presentation skils, energy level, meeting sales goals, professionalism.

Tell Guido, nevermind. I give up.