WP_User_Query with Serialized Array

wp-user-query.php

<?php

// Return users with a single language (English)

$args = array(
    'meta_key'     => 'wpcf-language-skill',
    'meta_value'   => 'English'
    'meta_compare' => 'LIKE'
);

$user_query = new WP_User_Query( $args );

// Return users with multiple languages (English OR German)

$args = array(
    'meta_query' => array(
        'relation' => 'OR', // can also be AND if you users must have both languages
        $array(
            'meta_key'     => 'wpcf-language-skill',
            'meta_value'   => 'English'
            'meta_compare' => 'LIKE'
        ),
        $array(
            'meta_key'     => 'wpcf-language-skill',
            'meta_value'   => 'German'
            'meta_compare' => 'LIKE'
        ),
    )
 );

$user_query = new WP_User_Query( $args );