This is tricky because it really depends on who your manager is and what they have planned for you. Personally, last summer I had to research IBM solutions and present them as pitches, contact clients regarding subscription renewals, and draft possible emails for clients.
I went through a rotational program which meant that my role changed every two or three weeks. I was able to work with five different departments within the Digital Sales branch of the business. Each rotation had different projects planned for the interns, but they all were interesting and challenging! Some of the things I worked on include: following up with clients via phone or email, researching (prospecting) potential clients, making various types of media (animated video, slide deck, written email, etc.) that summarized and taught an audience about a specific Digital Offering from IBM.
As a Summit Intern here at IBM, I work eight hours a day. The day typically includes working on multiple long term projects, conducting research about potential clients, attending corporate meetings, and completing short-term projects for managers. All the tasks are research based and require you to learn a lot about the company's portfolio. Presentations to clients and to your team are also very common as an intern here at IBM.