Retrieve user data from Firestore where id is equalTo

My request gives me a result but I can’t display the information in a Text Widget or other, what can I do?
Here is a screenshot of my code:
My Code

Here is the result in the console:
Result in Concole

>Solution :

Here documentData is a list of map.. so you have to access the child by its index

documentData[0]['nom'] //for example