Which built-in report from the reports page in PVWA displays the number of days until...

 The Privileged Accounts Inventory report in PVWA includes a column that displays the Age of the password, which indicates the number of days since the password was created1. This information can be used to determine how many days are left until a password is due to expire, based on the password policy’s expiration settings.

References:

CyberArk’s official documentation on PVWA reports provides a list of available reports and their descriptions, including the Privileged Accounts Inventory report which contains details about password age and other relevant information1.