Firebase is a real-time database, which means that the data is synchronized between different clients and with the backend server almost instantaneously. This implies that if the underlying data is changed by one of the clients, it gets streamed in real time to every connected client; hence, all the other clients automatically get updates with the newest set of data (without anyone having to refresh these clients manually).
Read:
To setup:
https://github.com/angular/angularfire2/blob/master/docs/1-install-and-setup.md