In order to fully understand what these programming languages are, I tried to explain only in one simple sentence.

<< HTML >>
HTML is a structure of a webpage and is used for (almost) all webpages, but it only shows black and white plain texts and images.

<< CSS >>
CSS is used to style and layout HTML/webpages, such as colors, sizes, fonts etc, and add animations.

<< JavaScript >>
JavaScript adds a dynamic movement to static webpages created only with HTML and CSS, and programs its behavior.

** Front-End Web developer needs these three above

<< Python >>
Python is a multipurpose language, used for developing web applications (on a server), automating tasks, and data analysis and machine learning.

<< Java >>
Java is a multipurpose language that runs on most platforms, used for mobile apps, desktop apps, web apps, games, hard ware devices, data analysis, and more.

<< PHP >>
While JavaScript is a client-side scripting language, PHP is a server-side scripting language, which can handle forms, data, files, cookies etc.

<< SQL >>
SQL is a structured query language (which is different from a programming language) that manipulates data stored in database object called table.