I think what you're after is the NETWORKDAYS function as it excludes weekends (and can exclude holidays).
see https://exceljet.net/formula/get-workdays-between-dates

You are aware that what you have in column C is text and not real dates, right ?
All of which are in the past and don't have any weekdays remaining.
Should it be that you have another column for the length of the bookings or something ?
Perhaps you can elaborate as to what you're after.