Work experience is a veeeeeery important part of the application for Business School programs.
Generally speaking, any kind of work-related experience will count... like your internships, certain projects for a company, or being a contractor. But there’s definitely quality differences here. First, it’s better that the experience is relevant to the program you are applying for. That seems obvious, but we can't stress it enough. Like for MSF, banking or financial analysis would be perfect and accounting work will be a little bit off. Second, some schools prefer full-time work experience, like MSF at UIUC or BC. Then your internship will not be that influential in the application. Hope this tackled your issue!