add_filter( 'rtcl_get_listing_types', function( $args ){

    $listing_types = array(
        'sell' => array(
            'en' => 'Sell',
            'ar' => 'يبيع',
        ),
        'buy' => array(
            'en' => 'Buy',
            'ar' => 'يشترى',
        ),
    );

    $lang = get_bloginfo('language');
    $result = array();

    foreach ( $listing_types as $key => $value ) {
        $result[$key] = ( $lang == 'ar' ) ? $value['ar'] : $value['en'];
    }

    return $result;
} );