Brand managers are responsible for overseeing any aspect of marketing related to a company's brand, and ensuring that all branding decisions ultimately result in stronger sales. To achieve that alignment, brand managers tend to work with multiple areas of marketing, like research, content, social, and design.

Marketing and branding expertise.
Research and analysis skills.
Knowledge of layout, colors and other design elements.
Mastery of written, verbal and visual communication.
Familiarity with latest marketing technologies and tools.
Understanding of sales and financial management.

Brand purpose is a company's reason for being and the things it stands for aside from the usual business goals and objectives. This why is usually to do with the customers it serves and the market niche it seeks to fill.