There are many types of languages that computer programmers need to learn in order to create a website. Some programmers chose to specialise in one or two whilst others decide that they wish to study all of them in order to give themselves more options when it come to programming a site and can make them more appealing to potential clients. Some common types of programming languages are C, C++, Java and PHP. All of these languages have pros and cons and every programmer you speak to will have their favoured choice for different reasons.
When you are having a website designed you may want to discuss the language that the website will be written in as some servers will only allow sites coded with one particular one. The majority of the time, people looking at the website will not generally know how it is programmed and the end outcome is often the same. As long as your site functions and looks how it should, it is not a major issue.