Brand registry approved - next steps

Hi,
I did my brand registry application yesterday, and today I received an email saying it had been approved. Now I still don’t have my product yet, but I’m just doing a draft listing, and underneath the box that asks for brand name, it says
“To list your products after your brand is enrolled, enter the brand name exactly as you submitted it for brand approval, and specify a unique value for the Key Attribute that you selected in the brand registry application.”
Can you explain what is meant by unique value for key attribute? Also I remember reading that Amazon will contact the trademark owner etc, but I’ve not heard anything?
Thanks in advance.