A Reservation marks the time as unavailable but the booking is not confirmed. To do this just log in to your BookingBug account and confirm the reservation from there.
To configure BookingBug to take Reservations; From the Dashbaord, click the Cog/Settings icon.
Click Dept Settings.
Click Change under either Public Bookings or Member Bookings. (BookingBug allows you to set specific bookings types based on if someone is a Member who saved login credentials for your Business or not.)
Click Take Reservations.
Bookings will now be taken as Reservations and will require Administrator confirmation from there.