Hi yunyunmao

Blog works with actions functions that can be override (hook) or edit them directly, the list below works as it is ordered.

Blog Template

//Open Container
add_action( 'kalium_blog_archive_content', 'kalium_blog_archive_posts_column_open', 10 );
//Start Loop - load elements
add_action( 'kalium_blog_archive_content', 'kalium_blog_posts_loop', 20 );
//Show Pagination
add_action( 'kalium_blog_archive_content', 'kalium_blog_archive_posts_pagination', 30 );
//Close Container
add_action( 'kalium_blog_archive_content', 'kalium_blog_archive_posts_column_close', 40 );
//Show Sidebar
add_action( 'kalium_blog_archive_content', 'kalium_blog_sidebar_loop', 50 );

Blog Items - the functions you have to hook to edit ( to add title, date , excerpt, category ), are listed below.

/**
* kalium_blog_loop_post_details hook
*
* @hooked kalium_blog_post_title - 10
* @hooked kalium_blog_post_excerpt - 20
* @hooked kalium_blog_post_date - 30
* @hooked kalium_blog_post_category - 40
*/
do_action( 'kalium_blog_loop_post_details' );

How to create new function for your request - this is what you need. 

/*
 * text before post
 */
if  ( ! function_exists('kalium_blog_post_text')){
       function kalium_blog_post_text(){
           ?>
           Content before post item each
           <?php
       }
}
add_action('kalium_blog_loop_post_details','kalium_blog_post_text',8);

Since your are inside loop you can call and ACF Field the_field('option'), or WP function such is the_title();

Important notice number 8 means when the code will be executed since the title is number 10 is first so 8 is lower and will be executed early before title.

Thank you.