Some icons on LG phones include those for missed calls, calendar event notifications, alarms, and new voice mail. All of these have a corresponding icon on the status bar of the phone's screen. A full glossary is available online at the LG website.
If a microphone with a red slash appears, for instance, the microphone is muted during the call. This means that those on the receiving end cannot hear what is said.
Another possible icon that is the alarm notification, which is an alarm clock with the arms at two o'clock with a red circle containing a white exclamation point in the center.