I am not understanding the statement in below link

https://help.salesforce.com/s/articleView?id=sf.task_view_survey_responses_usage.htm&type=5

When it says "including 300 free survey responses for each contract" what exactly it means?

Which Contract is it talking about?

How these free 300 Survey responses get counted? Are they per day\Per month basis?

Is it per Survey invite basis or based on SurveyRespnse record?

#Salesforce Surveys