To know about Picklist replace option, check the below link

https://www.infallibletechie.com/2013/03/what-is-use-of-replace-in-picklist-in.html

To know the status, check the below

1. Once you replace, you will be able to see a screen as below.

2. Click Backgound Jobs Page link to view the status.

Note:
You will receive an email too.

Cheers!!!