This Condition located on the Membership category tab in Search Builder looks at the Profile > Member tab for a person and at the status of the request you made for information from the person’s former church.
You want to find those for whom you have sent a 1st Request. Use the Condition Letter Status Equal 1st Request. That will find those for whom a letter has been requested, but not received. Once it is received, the Status would be changed to Complete. You can combine this with the Letter Requested Date and select a date more than 2 months ago. This lets you know those for whom you need to send a 2nd request.
These options be different for your church, as the System Admin can change these to fit your church’s processes.