Scientists and their departments need money for research, and they increasingly depend on funding from outside university. So they apply for funding from (inter-)national funding agencies, or cooperate with industry, external employers, or businesses. They may also want to make money out of the results, or spread results through the media to make sure their results get know and used.
This asks specific skills of you and your department, such as convincing non-experts, business negotiations, consulting skills, marketing your results, and dealing with the news media.
What exactly is the need for knowledge or applications by your external partner? How do you translate this to your research questions? How do you create an effective cooperation in which your and their needs are satisfied? How do you spread your results, make sure they get noticed in the news media?
That is what Selling Science is about!