Reverse Proxy simply explained

A reverse proxy is used to expose multiple (web) applications and servers. It does this by listening to any incoming request. Based on this request, it forwards the client to the correct application or server. In this way, you prevent clients from directly accessing all your applications which would introduce many security challenges.

A reverse proxy accepts any request on a particular port. Because of this, you also prevent opening many ports to clients to expose the respective applications to clients. The pattern of using a reverse proxy is, therefore, a lot easier to manage and also a lot safer.