What I am looking for is the Revenue which was 'earned' by a particular property in a month (sum total of the amount collected by the bookings for that month)
The Revenue by Stay Dates report should get you that number. It is the total non-refundable value of all reservations within a date range (e.g. a month). You can view this total per-property in the report.
One caveat, however, is that the Revenue by Stay Dates report will round the monthly revenue numbers to the nearest dollar. Also, this report will include all non-refundable money in a reservation even if it hasn't been collected yet. That means scheduled and overdue payments will be counted in this report.
Another thing to note is that if a reservation has stay dates across months (e.g. a June 29 to July 9), the Revenue by Stay Dates report will allocate money to each month by the percent of the stay in each month. For exampleReservation Dates: June 29 to July 9 Reservation Total Nonrefundable Value: $100 Nights in June: 2 Nights in July: 8 Percent of Nights in June: 20% Percent of Nights in July: 80% Revenue by Stay Dates in June: $20 Revenue by Stay Dates in July: $80