uiu-cse/inc/custom-blocks.php

<?php

function acf_portfolio_item_block()
{

    // check function exists
    if (function_exists('acf_register_block')) {

        // register a portfolio item block
        acf_register_block(array(
            'name'                => 'portfolio-item',
            'title'                => __('Portfolio Item'),
            'description'        => __('A custom block for portfolio items.'),
            'render_template'    => 'template-parts/blocks/portfolio-item/block-portfolio-item.php',
            'category'            => 'layout',
            'icon'                => 'excerpt-view',
            'keywords'            => array('portfolio'),
        ));
    }
}

add_action('acf/init', 'acf_portfolio_item_block');