Flask, Adopt a Pet, Step 12

Hello,

I learning the module of "Build Python Web Apps with Flask. Right now I am at the first project “Adopt a Pet”. I already searched the forum for some answers but I can’t find what I am looking for. I am stuck at step 12, I don’t really know what belongs in the for loop and why. When I look at other peoples codes I see something like enumarate but I have never seen this before. When people loop through the dictionary (keys and values) they don’t use the .items() method and I don’t know why. Can Anybody help me with these steps please?

https://www.codecademy.com/learn/paths/build-python-web-apps-flask