As per wiki intro, Ubuntu is a Debian-based Linux operating system and distribution for personal computers, smartphones and network servers. It uses Unity as its default desktop environment. It is based on free software and named after the Southern African philosophy of Ubuntu (literally, “human-ness”), which often is translated as “humanity towards others” or “the belief in a universal bond of sharing that connects all humanity”
As Linux is open source operating system. You can download it for free. Ubuntu mostly used on network server, because it is very secure out of the box, it doesn’t require external firewall techniques. Ubuntu is also used by programmers. So if you planning to be programmer this is for you. Ubuntu is not great in gaming and graphic related software things. So Ubuntu has very specific usage.
This course covers several topics which are essential to learn the Ubuntu. This course covers topics like how to get Ubuntu, understanding of Ubuntu desktop, What you can do with Launcher, How to use dashboard, Interface, How you can customize your desktop, Tour to system settings, How to do office things, how to work on internet, and how to get help.
So after learning this course you will be able to learn basic operation of Ubuntu. To learn more in detail you can go to http://ubuntuguide.org/wiki/Ubuntu_Trusty this website provides well documented help and guide.