In the Django tutorial for the first app in Django we have

from django.http import HttpResponsedef index(request):return HttpResponse("Hello, world. You're at the polls index.")

And then the urls.py has

from django.conf.urls import urlfrom polls import viewsurlpatterns = [url(r'^$', views.index, name='index'),
]

Now my question is what is the "request" parameter passed to the index function, also when the function index is called in urls.py it is not passed and variables it is just called as views.index in the line url(r'^$', views.index, name='index'),

The request parameter is a HttpRequest object, which contains data about the request (see the docs for django 3.2).

In your urls file, you are not calling the view.index function, just listing a reference to it. Django then calls the function when a matching request comes in and passes the HttpRequest object as a parameter.