Accessibility Label

Accessibility Labels provide metadata about your app, so that for example screen readers can access the elements in your app. They are critical for blind users, user with low vision, users with mobility disabilities and users with memory loss. Missing labels will make your app inaccessible for many users.

For some organizations, providing accessibility labels is mandatory, by law or by policy. In any case they are a good idea.

Apple has a video, Writing Great Accessibility Labels, which explains more.