A family of Microsoft word processing software products for creating web, email, and print documents.
If you click, you'll get a shortcut menu that includes suggestions for the first "error." If you click "Spelling..." instead, you'll get the same thing you'd get by pressing F7. But there is absolutely no need to do anything. If you are confident that your document doesn't contain any actual errors, you can ignore the icon. Or, assuming you have "Check spelling as you type" enabled, you can visually scan the document for words with a wavy red underline to make sure you haven't missed anything.