It is a period of time where the certificate’s Coverage is restricted. For Embrace policies, it is 48 hours for injuries and 14 days for illnesses.
What does this mean?
Conditions that occur during the waiting period may be excluded from your coverage as a pre-existing condition. That's to protect against a pet parent seeing illness symptoms in his dog or cat, signing up for pet insurance, and then going to the vet and claiming right away. As I've said before, pet insurance is for unexpected illnesses and injuries, and preventing these claims for known conditions keeps the premiums down for everyone.
The good news is that you don't have to go through the waiting period all over again when your policy renews as the waiting period is waived for policy and endorsement renewals.