Posts Page?

I have a layout I am trying to update for a client, and the way they have it set up is the home page is a post, while the other pages are actual pages. Then they have a category named ARTICLES, where they place all their articles. Right now, I can access a list of all the articles at theirdomainname.com/articles/, but I want to know which page in the theme is the one which I can edit this page? I can’t figure out which page I need to edit. Can anyone please help?