With the Divi theme blog module, there are two display option, grid or full post. Both of these allow for a short amount of blog content to be shown, or the full blog post content.

There is not an option to not show the content in the Divi blog module.

If you wish to have the blog post just show featured image or may be just the the title, you can configure that in the module itself. To remove the content of the blog posts from showing in the grid view, login the WordPress admin area and under Divi >> Theme Settings, enter the following custom CSS:

.et_pb_post .post-content {
display: none;