Promotional accounts are accounts with professional designations so you can promote yourself or your business. Anyone can create a promotional account to promote themselves. 

Note: All possible professions are not available for selection, these accounts are typically for those in the fashion, entertainment or media industry. 

For example, if you are a journalist and wished for people to see that is your profession and follow your journalism work, you can join as a Journalist account type. Then your profile and other areas will list you a journalist.  People will also be able to find you easier by searching for specific account types.