what do we mean by Match actions as 'Confirm' and 'Unconfirmed' while loading Items using import map

Summary:

I am loading Items using import maps but when I add items to Item batches after the process is completed I am seeing the items are still in process and I am not able to find the items using Mange Item screen

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):