What does this symbol mean, comes on after I hit the submit button

What does this symble mean, comes on after I hit the submit button

Since you have enabled unique question so that if the user fills the Form with the same email it would throw the error. However, it seems while customising the error message for this duplicate email field you have not saved the changes. The custom error message seems to be a blank one.

Please configure the error message:

Hope this helps!!

Thanks.

I need to have the ability of having the same email used so when
registering two or more dogs the client will have the same email, but
different dogs
Joel
...

You have the restriction, as my colleague advised:

Which will cause the error you saw if the same Dog call name is entered.

If you don't want that, you can just turn it off in settings page: https://www.jotform.com/build/83623710264150/settings

Let us know if you have any further questions.

Thank you!