As a beginner, I'll suggest you javascript.
Javascript is easy to start and understand + you can do a lot of real-world projects on javascript in no time (1-2 months). In today's scenario, javascript is progressing in almost every domain and if you want to do something on the web than mark my word javaScript is the king here. Once you understand the basics of JavaScript. You can choose any framework like react.js, angular.js or for backend web development node.js is also the best choice. Prerequisite : HTML, CSS.
Happy Coding...