As a PNP applicant, when you receive a nomination, IRCC has to verify that the nomination is attached to the express entry application number you provided and pertains to the right individual. An applicant can have multiple applications, but the UCI number remains the same. Since PNP applications only ask for EE application number, and not UCI, as many applicants (who are applying for the first time) may not have a UCI number allocated to them yet, or may have more than one application number, IRCC will look into this and verify.
As per IRCC
household is defined as:
Household: If there is more than one UCI for the same client, this is a data integrity issue. As there is no way to delete a record from GCMS once it is promoted, the UCIs must be linked by performing a household. When a household is done, the multiple IDs will still exist but they will be linked together.
If you do not have more than one UCI, then after verification, your application will be promoted, i.e. processed further. Many PNP applications are parked for this verification.
See
https://www.canada.ca/en/immigratio...ls/temporary-residents/terms-definitions.html
and search for household.