How does services work in FeathersJS?

What exactly happens when you mount a service to a path?

const feathers = require('feathers');
const NeDB = require('nedb');
const path = require('path');
const service = require('feathers-nedb');

const app = feathers();
app.use('/users', service({ Model: userModel() }));

function userModel() {
  return new NeDB({
    filename: path.join('data', 'users.db'),
    autoload: true
  });
}

And what does this accomplish?

const users = app.service('/users');  // what is users now?
users.create({ email: 'jane.doe@gmail.com', password: '11111', role: 'admin' });

via damonh