What other languages are good for web development?

Ruby (many frameworks available), Python, PHP (many frameworks available), Perl, Javascript (many frameworks available), C# (in the case of ASP.NET sites), node.js (which is really nothing more than Javascript really), and SQL databases are all used in web development. If I had to recommend learning one to start, it would be Javascript simply because it's client-side and allows you do use one (or many) of the vast amount of Javascript libraries (like jQuery or AngularJS, or even Enyo which is something I'm having fun with at the moment). You should have a solid grasp on the basics of HTML and CSS before or learn Javascript alongside HTML since it does execute in the browser. There are vast tutorials available on HTML, CSS, and Javascript, but my recommendation would be to use Codecademy and then use the Mozilla Developer Network documentation as reference. Google also has some excellent tutorials. I have links below.

For doing the front-end layout (the part that the user sees) HTML and CSS are the only option. Also on the front-end is JavaScript which is a real programming language that runs inside of every web browser. JavaScript can make your web pages more dynamic with the power of a real programming language.

For a server-side programming language, PHP is probably the more popular (but Python is an option). Another good thing to know is SQL for database work. Serious websites generally have a database. The most popular database that is available from web hosting companies is MySQL.

With a basic knowledge of these things, you'd be on your way to knowing enough to develop great websites.

Edit:

You should keep in mind that with these programming languages that a lot of programmer face the same sort of challenges and you can likely find code rather than writing it from scratch. For example, after you learn basic JavaScript, you'll find that jQuery (which is written in JavaScript) will solve common problems for you. The same with PHP. Once you understand the basics of PHP, you could use framework such as Zend PHP Framework which is built on top of PHP. There are even specialized libraries such as Magento that are built on top of the Zend Framework that would give you a big head start in doing eCommerce. There are probably other libraries that you could use for other types of websites.

If this is your first programming language then I suggest you start with HTML, CSS, and JavaScript. Most web applications require server backend programming as well as front end. The good thing about JavaScript is that thank to Node.js you can do both, front end and backend.

Any other server programming language would require you learning 4 languages. A lot of concepts from JavaScript are transferable when you are ready to learn another language like PHP, JavaScript, C#, etc.

I definitely recommend PHP for programming web applications. It is very easy to learn, but can be extremely powerful when used right, and there are tutorials online for just about everything in PHP nowadays.

Ruby on rails web language is good than for web development.

HTML and CSS can be used to make/design websites. Coding them for special funcions would be PHP and Javascript.

CSS and HTML are the basics. in case you desire to get into front end (layout) javascript is something you may desire to look into. Backend usually makes use of Hypertext Preprocessor, Python, Ruby, and different languages that are very complicated for a beginner. wish this facilitates!

Erlang might be worth looking into although it is not as popular as ASP, PHP and RoR.