This is mandatory page by s2Member plugin.
This page is used to showcase your Membership Options. This special Page is where you'll insert the Payment Button(s) generated for you by s2Member (or Pro-Forms; if you're running s2Member Pro). This Page serves as your lead-in signup page (i.e., you'll give visitors one or more registration options here, and they'll pay for the option they choose).
Your Membership Options Page should detail all of the features that come with Membership to your site, and provide a Payment Button (or Pro-Form; if you're running s2Member Pro) for each Level of access you plan to offer. This is also the Page that anyone could be redirected to (by s2Member), should they attempt to access an area of your site that requires access to something they're currenty not allowed to view.