How to calculate the sum of the contact records expiring soon on an account object in Salesforce?

Want to calculate the sum of the contact records expiring soon on an account object

Hi I am new toapex code and I am trying to caliculate the sum of the contact records where the email opt-in is about to expire. (email permission =  Date + 60 OR email permission = NULL). on Account object I want to display the count of these records. can somebody please help me with the code.