[Theme: Hiero] How to make category page show excerpts only, not the whole post?

Example of what I’m trying to get rid of: http://actioncamstarterguide.com/category/guides/

As you can see, the page is spammed with the posts, when the purpose of the page is to show only a brief description to get the reader interested. I have provided excerpts for all my pages.

Here is my Archives php template.

Thanks for your help.