The alt text (or alt attribute) is an extra piece of information that is added to your photos that is not visible to most visitors. The primary purpose of the alt text is to describe the photo to visually impaired users so that they still have a good user experience when visiting your website, even if they are unable to see the photos.
The alt text will also show when your photo doesn’t load (due to page load errors) and provides context to search engines as to how your photo should be indexed.
Using alt text for Pinterest will also help boost your SEO ranking.
How to add Alt Text:
Start by Uploading or Creating a draft from the Home or Drafts page
From the Pin draft, enter your alt text under Pin Image Alt Text (optional)
There you have it! Now the alt text will be shared to Pinterest when you schedule and publish your Pin.