The server that is hosting the site. The one you're trying to FTP onto. Your quality of life will be greatly improved if you can SSH onto the machine rather than using FTP, because the actual server software that hosts Python processes usually needs to be restarted. It's unlikely (but not unheard of) that you have anything like CPanel controlling a Django instance. It's
probably going to be GUnicorn or uWSGI, but there's a half dozen options on that front too.
I know that all sounds really wishy-washy, but I don't want to mislead you accidentally. The overall architecture isn't that different from a PHP app, but you might not recognize the configuration and file server technologies being used. The further along you get, the easier it'll be for people to figure out what's going on and help you at least figure out what files need to be changed.