Magento\Framework\Module is Magento framework component that allows to build modular applications with Magento Framework. It serves as an add-on to Magento\Framework\App component, and provides following features:

configuration reader and format with module versions, dependencies, and state (active/inactive)
module manager that provides all information about loaded modules
directory reader, that allows to read configuration files from module
ability to turn on/off module output in separate configuration application
module db data installers