Joomla is an open source, web site publishing service that is used with the browser. You can update pages or create new ones with it and its free!
WTH lol comeone in simple words.....be a bit less technical wot is JOOMLA wot do they offer and what are these JOOMLA templates?.
In my opinion the cadillac of Content Management Systems though it can be time consuming and frustrating to learn, but worth all the effort once you become familiar with it. You can end up building a power house content site if you know what you are doing. Read the link provided above. I will warn however their support forums has most questions answered is slow in getting feedback when you need support, but generally it's been asked and answered before.