The front-end is the part of your website that a user/customer sees and interacts.
e.g. A user types in the URL in a browser and the browser opens a web page. That web page is structured in a way, has its own design and performs some functions of supposed to perform some functions or specific actions. This whole thing constitutes the front-end of a web site or web application.
And the browsers handle figuring out how to turn these files into a functioning web page.
The job of a front-end developer comprises applying the work of designers to a web page by translating their well-designed layouts into real code. The front-end developer is the key between the designer and the back-end developer. Front-end developer turns the design into code and plugs in the data from the back-end developer into the right spots. He or she must also handle all of the possible interactions that the user may need to make with the page.
Front-end development is easy to start and is notably less complicated when you go several levels up. But you will need to be extremely conscious of who are your users and how they will be interacting with your web page. This may mean gaining a more robust understanding of accessibility and things like responsive development down the line. However, you first need to build your knowledge and learn the fundamentals of the front-end ecosystem.
I am starting a series of articles to share things that will help you become a front-end developer. If you want to get notified whenever I post a new article in the series, feel free to subscribe to my email list or follow me on twitter.