Your DMR-ES10 is of 2005 vintage. It can record to DVD-R or DVD-RAM discs. Don't attempt to record to "+" discs as they are not supported by this model (see pages 4 and 5 in the Operating Instructions).
Let me guess. The disc you inserted is blank. In the SETUP menu you have the EP (recording mode) set for 8 hours instead of 6 hours. You have the recorder set to the EP recording mode.
The R8:00 indicates that there is 8 hours remaining recording time on the disc.
If you set the recording mode to SP you will see R2:00 and if you set the recording mode to LP you will see R4:00, etc., (see page 15 in the Operating Instructions).