The Profile Server is a core component of the Internet of People architecture. If you are not familiar with IoP, the Profile Server itself will probably make not much sense to you. If that is the case, it is highly recommended to explore IoP first before you start with the Profile Server. See the IoP architecture post linked above and then possibly continue with more articles about IoP. Also you can try this specific post: The Profile Server talking about this topic.
Are you interested to run the Profile Server software on your machine? See Installation file on how to proceed.
To get more information about Profile Server's internals, check out Architecture Overview. This is a must read for anyone considering joining the development of the Profile Server itself.
If you want to develop a client application (or a server in a role of a network client) that connects to the Profile Server and consumes its services, you will be interested in Introduction for Developers of Client Apps.
TODO file contains possible improvements that are being considered, some of them are on the project's roadmap and will be implemented in upcoming versions.