I have read many explanations on reverse proxy I still don't understand the interest. Could someone really explains in plain english
A reverse proxy is a proxy that retrieves data requested from a client from one or many servers. In many cases these are used for load balancing.
They might be also used when there are many web servers and a single PP address, the reverse proxy would receive the requests to port 80 and forward them to the servers that might be listening on different ports on the same machine (or port 80 on another machine) and then forward the response back to the user.
Also I've used a reverse proxy so I can use Apache's authentication / rewrite modules in front of another insecure standalone application that serves pages by itself.