The next line is an if conditional that uses the request.method property to see if the HTTP request method is POST:

if request.method == "POST":

Because the initial request to the URL arenas is a GET request, the code initially evaluates the if conditional as False, skipping the indented code section to the bottom of the view to return the template index.html and the now populated form:

return render_template('index.html',form=form)

This function returns uses the render_template function to return the template called index.html and passes the populated ArenaForm variable called form into the template, making it possible for the Jinja2 templating system to generate the completed web page and send it to the requesting web browser. All of the template's double-bracketed variables are filled in with the corresponding data from form (for example, the selections are added to the drop-down list).