Libraries notoriously struggle to make money. Many of them function as charities, and those which don't are often state-owned. If you don't know anything about how the internal functions of a library operate, you might think that a services director does little more than decide which books go on which shelves, and you might even assume that such people are volunteers. They aren't.
A library director is responsible for all the staff inside of that library, setting usage and entry policy, and deciding what, if any, educational and support programs that the library offers to its community. You'll also be responsible for the budget, which as we've already established might not be great! There's a lot of responsibility on your shoulders, and so you'll be paid well to help you bear it. An experienced librarian with a suitable degree would make a good candidate.