Can someone explain me partial in ruby on rails : I am trying to figure out how partials works in rails.

Here is code : 

<%= render "layouts/appended_pages", pages: {partial: "items",
                                             collection: @results,
                                             locals: {user_flag: false}} %>

I understand that this render will render _appended_pages but what will do part with pages:  ? Can someone explain me  how it works    