Expose Rest API in local app for Android app

I am new to web development and would like some help. I am making one android app that makes some REST calls to get and post some data. These rest of the calls will be done on my own server. Now for development purposes I don't have this server. How can I develop rest apis on my local machine (localhost) and make it available to my android app over Wi-Fi? So my question is how should I do development (setup) where I can use my local machine and set up a server and use it in my android app.

I don't understand what setting and what to do. Some pointers in the right direction and I can use it according to my need.

thank