YaST2 is the System Management utility of the SUSE Linux Distribution. It is the second version of the former YaST. It can be controlled via a text interface (ncurses) or via a GUI. It can be used to install software, configure hardware, change your firewall settings and much more. When you install software with it, YaST2 automatically resolves the needed package dependencies.
To get an overview menu what you can do with yast2:
To get an overview which applications you can install with yast2:
yast2 -i firefox