FTP stands for File Transfer Protocol.
FTP is basically connecting to your server, which is where all your website files are located.
A good rule of thumb is usually on servers your root directory (where all the files are) is called either public_html or www.
It's always worth noting that if you’re unsure ask your hosting company.
FTP’ing to a sever consist of 4 bits of information… FTP Host: this can be a ip address (eg 192.168.0.1 or similar) or a url such as ftp.yourdomain.com FTP directory: this could be but is not limited to / or /public_html or /www but please ask your hosting if you unsure. FTP Username and password: this is so it’s a secure server.
Uploading - once you have your ftp details it fairly easy - you can use free software like filezilla or some/most hosting companies do have a ftp client in your account page, once again contact your hosting company for further details. There is an option for us to upload your files if you need it.
Here are some useful related content... Uploading files through Godaddy - https://support.godaddy.com/help/article/96/uploading-files-to-your-website-ftp?countrysite=uk