it means you need to run the command the error message told you to run.. did you run it ?
it's telling you that an install was interrupted or failed and there are packages that were partially installed and still need to be configured before you can install anything else.
Open a shell, su- to root and run the command.
dpkg --configure -a
Reconfigure an unpacked package. If -a or --pending is given instead of package, all unpacked but unconfigured packages are configured.