I'd recommend reading the official Hashicorp website for that, but the gist is that nomad is another way of deploying apps in containers (similar to kubernetes)

I'd recommend reading the official Hashicorp website for that, but the gist is that nomad is another way of deploying apps in containers (similar to kubernetes), consul is how apps find other apps to talk to (kinda like DNS but with health checking built-in so they don't get stale info), and vault is how apps retrieve the credentials they need to connect to other services.