FTP stands for File Transfer Protocol which is nerd-talk for “this is how you move files around the Internet”. This becomes a skill you’ll find necessary when you need to move the website you’ve created on your home computer onto the server that is hosting your site. Unless you have physical access to that server you are forced to upload those files over the Internet. Most web hosts provide a means of uploading files to your space on their server but not all will provide a nice way to do that in bulk, that’s where ftp comes in.
In the modern era you don’t actually have to know everything about this protocol to use it and there are plenty of third-party products out there that will assist you in using FTP. Since I like discussing free programs on this website I’m going to walk you through how to set up and use FileZilla for your ftp needs.