The term "Wrapper List" is not something related to Batch Apex, so probably you would need to ask for more information about what they really want.
A Batch Apex is a feature that helps you to execute a process asynchronously. I'm just guessing but maybe they only want you create your own Iterabale class in order to be used in the Batch Apex. Find here (https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_iterable.htm) an example. But really, I would ask for more information instead of doing something they don't expect.
A wrapper class is a class you implement to extend/protect the functionality of a Standard/Custom object. The usual scenario where you need a Wrapper class is when you don't want to expose the objects you're using on a Visual Force Page.
Bad Practice:
<apex:Page controller="MyController">
....
{!acct.Name} <!-- You have direct access to the sObject here -->
....
</apex:Page>
Best Practice:
<apex:Page controller="MyController">
....
{!myWrapper.acct.Name} <!--Wrapper class provides an extra protection layer -->
.....
</apex:Page>
In any case, you should always bulkify your processes, and having a List of wrappers is good practice. Thus, a "WrapList" is nothing more than a List of Wrappers.
List<MyWrapperClass> wrapList = new List<MyWrapperClass>();
The rest of the implementation depends on what they wanted from you in the interview.
A Batch Apex is a feature that helps you to execute a process asynchronously. I'm just guessing but maybe they only want you create your own Iterabale class in order to be used in the Batch Apex. Find here (https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_iterable.htm) an example. But really, I would ask for more information instead of doing something they don't expect.
Hope this helps.
The usual scenario where you need a Wrapper class is when you don't want to expose the objects you're using on a Visual Force Page.
Bad Practice:
Best Practice:
Another scenario would be where you want to keep track of the records you want to save/delete etc. (i.e. a checkbox)
https://developer.salesforce.com/page/Wrapper_Class
In any case, you should always bulkify your processes, and having a List of wrappers is good practice. Thus, a "WrapList" is nothing more than a List of Wrappers.
The rest of the implementation depends on what they wanted from you in the interview.