shortcode-category.php

// Add Shortcode
function button_category($post_id) {
    $category = get_the_category( $post_id );

    $return = '<a href="'. esc_url( get_category_link( $category[0]->term_id ) ) .'">Ver ' . $category[0]->cat_name . '</a>';

    return $return;
}
add_shortcode( 'button-category', 'button_category' );