On a nanny job posting, what does: vacation relief mean?

[kandy_chik]

Im looking for a nanny job, and this posting says: Also this person could be our vacation relief Nanny so there would be extra shifts.

what does vacation relief mean?

 

[Chelsie]

Either a fill in or they may be asking for you to help with the kids on their vacation (as in going on vacations with the family)