Beginner question: Vector tutorial

Hi guys I’m new so hopefully this question wasn’t asked before but I’ve got a question about the vector tiles tutorial

After setup and running

DATABASE_URL=postgresql:///brussels ./pg_tileserv

I’m able to see the vector map being hosted locally in my browser (as is expected I’m guessing) and the map is centered in Brussels, everything’s great!
But here’s my question… I’m able to zoom out and collect street data from other cities (Seattle, Denver, etc) in the same browser, does the brussels.osm.pbf (defined in the tutorial) contain vector data of every street in the world? I’m confused what this file contains as opposed to for example (which contains all the data from Europe). It seems like every .osm.pbf file contains vector street data of every city on earth