There are many logistical concerns that go into managing a construction site. Their responsibilities include ensuring that work is on track to meet a deadline, keeping an eye on the budget, and making sure that OSHA regulations are followed - a lot of mental work has to get done while the hammers are swinging. That is the job of the site/project manager.
The site/project manager manages the construction project so that the workers can focus on their tasks. They often start working before ground is broken on a project in order to draw up a budget and construction plan. The site/project manager is also responsible for supervising workers and communicating with clients.
Most site/project managers have bachelor's degrees, although not all of them do. Previous project management experience is also very important. It probably comes as no surprise that about 80% of site/project managers are men since the whole industry is male-dominated, but that doesn't mean things can't change in the future.