WooCommerce: Change Out of Stock text

code.php

add_filter( 'woocommerce_get_availability', 'wcs_custom_get_availability', 1, 2);
function wcs_custom_get_availability( $availability, $_product ) {
   

    // Change Out of Stock Text
    if ( ! $_product->is_in_stock() ) {
    	$availability['availability'] = __('Currently Unavailable', 'woocommerce');
    }

    return $availability;
}