The Services Manager allows you to easily take control of programs that are automatically started each time you use your computer. Services are important programs that are started before any other Windows program. They usually take care of networking, web publishing, firewalls, etc.
On the left you have a list with the services that can run in the background. You can enable/disable them by clicking on the circle next to them. If a service has a checkmark, this means it is enabled, and if the circle is empty, the service is disabled.
By default, the Microsoft services are hidden from the list, to help you look for the services that you want more easily. You can unhide the Microsoft services by removing the checkmark from "Do not show services from Microsoft" on the right.