Multiple dokku containers on one Digital Ocean droplet?

Question

DigitalOcean

I'm just starting to understand the organization of servers, VPS, domain names and all this - please help me put things in order in my head.
I have a droplet on digital ocean, a node and dokku are installed there, there is a dokku application in which a telegram bot is spinning. What is a container (application)? Judging by the dokku help, I can deploy several dokku applications on one server, but how can I assign a domain name to each application? Or one droplet - one domain?