There's really a big clue in the title of this job with regard to what it involves. Data scientists apply scientific analysis to pieces of data and draw conclusions from it. The most prominent data scientists work either in formal science or, interestingly, politics. Data science is invaluable to politicians and political parties, as it allows them to see what their typical voter looks like, what their interests are, and what else is likely to appeal to them in terms of policy. They can then deliver their message down the channels the data scientist gives them.
Data scientists will also be used in marketing, as they can extrapolate data and use it to tell a company who is or isn't buying their products, and what they can do to change those numbers. A senior data scientist can set the marketing strategy of a whole company. IBM predicts that this will be one of the fastest growing job sectors in the world during the next five years, so it's a good time to get involved.