UTC is short for Coordinated Universal Time and can for most practical uses be translated to the older Greenwich Mean Time (GMT) standard, see this wikipedia article for details:
We use the UTC-standard to give an absolute time reference that easily can be translated to local time zones around the globe.
To translate UTC to your local time you can use a webservice like http://www.worldtimezone.com/ or look att the map below.
A common way of describing local time related to UTC is like "UTC+2" (like we have in Sweden during the summer daylight saving time, in the winter we have UTC+1). So when we for example say that a patch is due 08.00 UTC that means 10.00 local swedish time (in the summertime).
Similarly e.g. the eastern part of the US uses EST (Eastern Standard Time) or EDT (Eastern Daylight Time) which is UTC-5 and UTC-4 respectively.