This Pro tutorial provides the code for getting the index of each post in Bricks‘ query loops.
This can be used for either outputting the post number (screenshot below) or for checking for nth post and conditionally outputting elements (Ex.: How to Insert Element(s) Between Query Loop Posts in Bricks).

Note: If you have BricksExtras installed, there is no need to use the below custom function. BricksExtras comes with it. Check the Dynamic Tags doc page.
Step 1
Add the following in child theme‘s functions.php or a code snippets plugin:
/**
* Get the current loop index
*
* @return int
*/
function bl_get_loop_index() {
if ( method_exists( 'BricksQuery', 'get_query_object' ) ) {
$query_object = BricksQuery::get_query_object();
if ( $query_object ) {
$value = intval( $query_object::get_loop_index() ) + 1;
}
} else {
$value = 0;
}
$value = isset( $value ) ? $value : 0;
return $value;
}
Note that generally index starts with 0. But for the sake of convenience, we are adding 1 so it starts with 1.
Step 2
Set up a query loop.
Add a Basic or Rich text element inside the query loop.
To output the loop index use:
{echo:bl_get_loop_index}
