I'm relatively noob to the world of web developpement, and after learning the basics of HTML5/CSS3/JavaScript/jQuery I've started to learn AngularJS.
The problem is that as I am learning AngularJS, I don't understand what will be the point in learning a server-side language like PHP, it seems like AngularJS can do all the job (UI, views, routing, ...)
I think that the only reason would be to store data (but even that, I can use JSON files, no?) and if it is, how much PHP do I need to learn? (or which parts of the language)
Thank you and sorry for my english.
Angular is a tool for a specific sort of job. It is not the tool for every job, and neither is PHP.
If you are writing an application that can live client-side, then you can certainly generate all of the dynamic components you need with Angular. There are many web applications out there that are entirely client-side. There are even more that function client-side and talk to a simple API server for their back-end.
If you are creating a web page that is not interactive, then there is little reason for something like Angular. There are benefits to having the DOM filled with content ahead of time. SEO is usually the biggest reason, but you might also consider clients that have disabled JavaScript (if you care about those).
Are you building something that is interactive? Consider a heavier client-side framework like Angular. Are you building a web page that is content-driven? Consider rendering your pages server-side. In the end, you will likely end up with a mix of both anyway.
A large consideration is security. Everything client side is exposed to the world. If the back end is just data storage without validation or protection except as written inside the client, a malicious user could push whatever data they wanted into your site. In addition if you are exposing code that is the core of a business inside the client, every user can see that as well.