Hi @ASNeelima,
Reconciliation based on email will help to identify the record from source (file) and destination which is profile resource.
From your screenshot for example, if i have profile with email as abc@yyy.com but don't have any first name, last name. When i load the file with row that contains same email, first name, and last name, It will update the profile with first and last name since profile with abc@yyy.com is already found in profile resource.
Hope this helps.
Take a look at this documentation for additional information,
https://experienceleague.adobe.com/docs/campaign-standard/using/managing-processes-and-data/data-man...
Thanks!
Thanks, Sathees