WCAG 3.3.5: Help
WCAG 3.3.5 Help is a level AAA success criterion from WCAG 2.0. Context-sensitive help is available for forms.
People unsure what a field wants need an explanation next to it.
How to test
Look at unusual fields such as a VAT number. Help text should be beside them.
How to fix
Add a short hint under the label.
Example that fails
VAT number has no hint.
Example that passes the check
The hint says the number printed on the invoice, with an example.
Shopify
Add help text under custom fields in the theme form.
WooCommerce
Use the field description on checkout fields.
WordPress
Add the form block's help text.
Wix
Fill the field description.