functions.php

add_filter( 'wc_password_strength_meter_params', 'my_strength_meter_custom_strings' );
function my_strength_meter_custom_strings( $data ) {
    $data_new = array(
        'i18n_password_error'   => esc_attr__( 'Come on, enter a stronger password.', 'theme-domain' ),
        'i18n_password_hint'    => esc_attr__( 'The password should be at least seven characters long.', 'theme-domain' )
    );

    return array_merge( $data, $data_new );
}