Computer programming is a bunch of instructions that tell a computer/software program what to do in a language that the computer understands. These instructions come in the form of many different languages such as C++, Java, JavaScript, HTML, Ruby, and Python.
Using the appropiate language, you can program/create all sorts of software. Such as a program that helps scientist's with complex calculations, a database that stores huge amounts of data, a web site that allows people to download music, or animation software that allows people to create animated movies.