In linguistics and grammar, a pronoun is a word that substitutes for a noun or noun phrase. It is a particular case of a pro-form.
IP Routing is an umbrella term for the set of protocols that determine the path that data follows in order to travel across multiple networks from its source to its destination. Data is routed from its source to its destination through a series of routers, and across multiple networks.
IP forwarding should be enabled when you want the system to act as a router, that is transfer IP packets from one network to another. In the simplest case, consider a server with two physical ethernet ports which is meant to connect to two different networks (say your internal network and the outside world as provided by a DSL modem).