The job of a group project manager is pretty much exactly what it sounds like. They help execute a project that a team needs to get done. Of course, the nitty-gritty of seeing a group project through to the end is a lot more complicated than it seems, as anyone who's done group work in school knows.
The group project manager oversees the logistics of completing a group project, from ensuring that the project stays within budget to setting deadlines for deliverables within the larger project. The group project manager also needs to be good at wrangling people. They help team members meet their goals and coordinate with supervisors when necessary.
The group project manager can find work in a variety of industries, from informational technologies to telecommunications. Basically, any company that needs groups to complete projects might need a group project manager, someone with project management experience, and excellent people skills.