The PHP programming language is a server-side HTML embedded scripting language.
Let‘s depict the sentence. The PHP language runs on the server-side. This means that the execution (read starting) of the scripts are done on the server where the web-site is hosted. HTML embedded means that you can use PHP statements (read a piece of PHP code) from within an HTML code. PHP files are returned to the browser as plain HTML.
The last piece of the sentence – scripting language – is a little harder to explain, but we will give it a go. A scripting language is a form of programming language that is usually interpreted rather than compiled. In programming languages such C or C++ you compile the program (permanently) into an executable file, before you can execute the program. A program that is written in a scripting language, is interpreted one command at a time by a command interpreter (Command interpreter is in most cases an executable written in another language (for instance C/C++) than the scripting language.) Some other examples of scripting languages are Perl, Phyton, Java and Ruby.