I'm sure guys like FreshFromATL, TypeUserName and others can give more clarification, but here's a basic rundown for fellas looking to understand what they are getting into.
General purpose languages are those that are typically used to produce a variety of programs, from desktop applications to networking applications, to being used on the server-side. C, C++, Java, and C# are examples of general purpose languages. Python and Ruby are also technically general purpose applications, but due to the nature of them being scripted languages, they are typically used for more specialized purposes. Python is a language being pushed heavily by Google and it's being used a ton in academic circles. It is a language that allows you to produce things a lot quicker than a language like C, but it delivers nowhere near the performance... hence, it can often be used as a 'prototyping' language to produce a prototype of a program, which is then recoded in C/C++ for performance. It can be used for a variety of applications, but you generally don't want to use Python for something that requires top-notch performance, but it's benefit is that it is quick to produce things with.
Assembly is an extremely low level language. A language like C/C++ is higher level than assembly, but still low level. These are general-purpose languages allow you to get closer to the machine. These languages are generally more difficult to work with than the higher level, more abstracted languages, but these languages are critical in applications where performance is crucial such as operating systems or games. Learning these languages will help you know what's going on 'under the hood', since you have much more access to hardware and memory. They generally take a lot longer to 'do stuff with' than some of the higher level languages, hence using them for performance critical applications and not general programs that aren't performance critical.
Although languages like Javascript or Ruby can be used in a variety of environments, typically they are used in a more specialized environment. Javascript can actually be used to make Windows 8 apps, but it is typically used for cilent-side programming and even server-side programming via Node.js. Ruby is in theory general purpose, but in the real world, it is used primarily for server-side scripting via the Ruby on Rails framework.
Now, when I say something like Ruby on Rails is a 'server-side framework', what that means is that on the web, there are typically two sides. There is the client-side and the server-side. The client side refers to what happens in your browser. It involves HTML, CSS and Javascript. if you produce an HTML file on your computer and open it up locally in your browser, what you are seeing is the client-side. Client-side uses HTML for structuring documents, CSS to provide the style, and Javascript to provide interaction. When you see Disqus comments on different webpages, why it is able to update in real time without you refreshing the page is because of Javascript interacting with the web page in real time. For example, these comment sections send requests to a server, is returned some data, and Javascript uses that data to update the page via the DOM (document object model) in real time. When you are programming on the server-side, you are scripting how a server will interact with clients who request data from it. Typically you will also have to learn some database management program along with it (MySQL, Postgresql, MongoDB, etc.). For example, if you have a message board, when users submit posts, it sends a request to the server, the server stores the users information and that post in a database, and when users request data, such as to display a post, the server interacts with the database, pulls up the necessary information and sends it back to the client.