The term SPA is self-explanatory; one SPA web application is an application that holds all its functionalities in one single web page. This changes how we conceived web development for a typical web application; instead of making a request to the server every time a user changes the section in the application (e.g. clicks on a link), the front-end client handles all those changes without requiring the transfer to another page or a page reload.
It is, in broad terms, an MVC pattern framework with which a developer can design full, reusable components. Its main feature is two-way data binding (A strategy that is commonly used to build Flex Applications).
Right now we are developing an SPA application with Angular and we are starting to see huge benefits making use of it, we will keep posting here about our progress.