FTP is a short for File Transfer Protocol. The word ”Protocol” basically means a set of rules. So, File Transfer Protocol is basically just a set of rules for file transferring.
It is also meant for uploading and downloading files. For an instance any two systems that use the same network can transmit files using FTP Protocol.
For example, your friend sends you a file. You press download. That is the part where you and your friend connect using the same network and that process is called FTP download which is the same thing as FTP.