Netlify Forms is Netlify's form handling for sites running on that platform. You add an attribute to an HTML form, after which Netlify detects the form at deploy time and processes submissions, without a backend of your own or extra JavaScript. Submissions can be viewed in the site's admin panel, notifications can be sent by email or by HTTP POST to an external service, and there are spam filters and a reCAPTCHA integration.
Netlify Forms is part of Netlify, Inc. in San Francisco, a US company with affiliates in countries including Canada and the United Kingdom. The documentation does not say where submissions are stored. The privacy statement says data may be kept outside the country of collection, and that for transfers to the US Netlify is certified under the EU-US Data Privacy Framework and uses standard contractual clauses. For enterprise customers it refers to a data processing agreement. A European organisation collecting personal data through forms is advised to check the storage location and processing terms in advance.